Make sure your sequencer is outputting "MIDI Clock" on the MIDI port that your Virus MIDI-IN is connected to.

At the end of the "CTRL" menu, there is an option called "ClockRx". Set this to "Auto".

If you are designing a sound that you would like to sync with MIDI clock, you can adjust the following parameters to pay attention to the clock signal:

* Delay Clock
* LFO1 Clock
* LFO2 Clock
* LFO3 Clock
* The Arpeggiator
Each of these items can have a period from 1/64 note to 4 measures.