Vanguard Will Not Switch Cameras

Questions

I cannot switch cameras from my computer. What should I do?

Can you switch cameras via remote control? If not, please get that working first.
Is your CM19A attached to the computer? It is required for camera control.
Does the CM19A's LED blink briefly when you click on a camera motion button? If not, it may have an issue.
In Options-Cameras, are the correct cameras selected, and are they at the correct House and Unit code? If not, camera control will not work.
You may be seeing a radio issue. What objects lie in a straight-line path between the CM19A and the cameras or the TM751 module? Try repositioning the CM19A.
If you hold the remote right next to the CM19A, can it still switch the cameras? If not, relocate the CM19A.