Virus TI (Os3.0) syncing in host DAW

[TheHobbit]

Hi

Using Cubase 4.5 + Virus Ti os 3.

I seem to get random problems where the virus is receiving midi signal, I can see it in cubse and other midi kit works but I get no sound.

All other synths and vst plugins are sounding fine going out via the Mackie Onyx firewire interface which is the ASIO driver selected in Cubase.

What am i doing wrong.missing.

I have tried selecting both USB and Analogue outs in the utilities function in virus control and also set Various outs and ins in the setup panel.

The USB is working and have tried other usb ports on the rear of the PC.
The cables from the analogue out work fine, when the sequencer is not loaded and all midi signals are carried out and I get a sound from the Virus.

Please help