making pianoteq work in Cubase

Hard to say for sure, but it sounds like a routing problem.  Start by confirming that VSTs outputs are going where they're supposed to be.  Then I'd look at volume settings in PTQ/OTQ.  I'd start from the end of the signal chain and work back testing everything, though the fact that you're getting sound from other sources means the problem is probably in nearer the middle of the chain.

Off hand, you're signal chain will (probably) be as follows:

MIDI Input (physical or virtual--mapped in Cubase) > MIDI connection to PTQ VST (if you're using something like a MIDI channel that routes to the VST) > Internal PTQ volume (controlled by lots of things like microphone settings and the main volume slider) > Any audio aux sends (so back out in Cubase) & the main VST Audio Out > Any main or aux buses > Main Out > Hardware/ASIO I/O (configured in the Studio Settings in Cubase, also useful to use Control Room if you're running the full version of Cubase)

To better give you advice, knowing which tier and version of Cubase you're using and what OS, etc. might help, if the above doesn't already point you to the issue.

The answer is no. The piano and organ teq work perfectly as stand alone.
In Cubase both for organteq and pianoteq, when I play on the keyboard the keys do NOT go down.
When I click on a key in the Pianoteq/Organteq display, I see the volume meter for the track respond and sound is now coming out but only when i use the mouse.
I am not sure how to respond to the last question.
thank you

Professor Young, your comments are always appreciated. Do not ask me how, I followed your advice and reviewed the chain of connection. For some reason, the cubase throws the inputs and outputs off to default or nothing every time the USB drive to the sound module (UR44) and needs to be re-set up manually every time, Its very frustrating. But I can get the sounds out now. thank you.

PS:  Here is the twist though, as I have only played the Pianoteq and organteq as stand alone. Now that I am trying to use it in cubase, I feel a delay from the time of push the keyboard until the sounds comes out. Something I do not experience with the stand alone version. So I may need to change something in the delay or pre-delay in cubase. Just don't really know where to start.
 

You're very kind!

What you describe is sadly familiar.  Cubase's handling of MIDI, especially of a variety of MIDI devices by USB is inconsistent at best, generally Cubase will just disable a device under circumstances that most other applications wouldn't.  Ironically, Dorico (which is also from Steinberg) and Standalone Modartt apps do much better handling USB signal loss than Cubase does.  While much of the reason is likely that Cubase tends to need MIDI devices that are dedicated and under total control of the DAW (my guess would be primarily for clocking reasons), I've never liked that once Cubase has any sort of I/O issue with a prior device, it silently disables it and you need to manually go deep into the settings (often after restarting the application) to get it to see the device and allow you to enable it again.  MIDI issues with multiple USB devices that may have connectivity issues is among the single greatest reasons to keep VSTis running Vienna Ensemble Pro (but I digress) so you can open a close Cubase half a dozen times working out a hardware I/O issue, as it isolates Cubase crashes (which are more frequent than I'd like admit) from needing to reload a full orchestra (or for some colleagues three orchestra's worth) several times a day if the project or your hardware goes haywire.

There is one thing you can try or consider, and that's a USB MIDI Host Box, which then will plug directly into your UR44 module's 5-pin midi ports (assuming the neither of your keyboards have 5-pin already).  Whenever I'm trying to work in Cubsae, I have a nightmare with my 5-6 USB MIDI devices--so I usually try to generate MIDI data in another application like Dorico or another DAW (including probably with the greatest frequency the Standalone apps) and then wrangle Cubase with note data rather than have it be the direct connection so that Cubase can entirely ignore the majority of my USB devicves.  That said, in my case, Cubase will not work at without my Behringer UMC1820, which like your UR44 has old school 5-pin MIDI, and I've never had signal loss or availability issues with the device(s) I plug into the main interface, as the main interface can't lose MIDI signal as it would lose all signal and Cubase would either crash or disable the entire active project until the interface behaved correctly again.  So USB MIDI Host Boxes allow you to turn a USB MIDI cable into 5-pin (theoretically), which would solve the high-availability issues you're running into with Cubase.  That said rigging together multiple boxes for multiple keyboards could start getting a little hairy--theoretically doable but not guaranteed to work smoothly.  The fact that it's a Steinberg interface will also mean greater reliability with Cubase for MIDI.

The reason the standalone doesn't suffer from this, is it's much more leniant and permissive by default for I/O issues and restarting Standalone is trivial, while doing that in Cubase is anything but.  I've had the best results "recording" raw MIDI data into the Standalone app for most things and then import the MIDI data that PTQ/OTQ records into Cubase projects, where you can quantize or do whatever you need to treat them like another MIDI data, which then you can internally port to a VSTi or place the MIDI data directly into the VSTi's channel (it just depends on how your template is routed for your convenience).  (For what it's worth, I've always followed Trevor Morris's advice to have a master orchestral composing template that you only change once every six to twelve months, as the amount of routing and work needed for as many instruments as that involves is just impossible to maintain if you're constantly making changes, so you set aside a few weeks a year for adding new stuff or fixing bugs, and otherwise leave it alone so you can focus on composing and scoring the rest of the year.  That said, that's a concern only when your default template starts to be anything over 50--or more like 80--instruments.)

There will likely be some slightly greater delay no matter what you do, as your UR44 and the Cubase settings are giving your DAW the global clock and ASIO delay--plus CPU load is also handling clocking concerns, FX, and other functions of the DAW leaving less headroom in practice.  Under the different Studio setup options, you should be able to manage your ASIO driver delay and similar settings (which are presumably lower in whatever interface/output you're using in Standalone than in Cubase).  That, and Standalone's export at high quality settings doesn't need to clock against anything and can just effectively run in the background while exporting.  Also, any DAW will have different abilities to throttle the behavior of your VSTs than any standalone VSTs will themselves (basically things like Cubase's ASIO-Guard), which can cause highly beneficial or highly disastrous unexpected outcomes.

Also, if your Standalone is set to 44.1kHz through something like Windows Direct Sound and your DAW is at 48kHz (moreso with 96kHz or 192kHz), that will directly change the CPU load that the VST takes which--while not adding delay--decreases your polyphony ceiling and can lead to more cracking artefacts during real-time playback.  So, you can start lowering your ASIO delay and also check your project settings that your UR44 is using a sampling rate that is reasonable for your project, and that should give a closer experience for Cubase compared to Standalone.  Now, it's a different matter when you have waveform assets in a project that are already sampled, but for plain MIDI playback, you likely want as low a sample rate and ASIO buffer rate as possible, to give the most real-time playback--especially if your settings including dithering assets to a new project sample rate or bit rate.  Generally, you want to trial-and-error your way through the lowest settings possible (that still sound good) and keep increasing the buffer rate until all artefacts (or at the most bothersome ones) go away.  Bit depth really shouldn't be an issue when comparing 16- 24- and 32-bit (as certain environments will generally choose for you--like Cubase will--or at least should--do every internal calculation it can at 32-bit until you render/bake to a 16- or 24-bit waveform), but lower bit depths can also take some CPU load off or allow for lower buffer rates, but again, that's more limited how you can or can't control that one.