Ultimatte 12 4K background input

Hi,
can I connect my PC or laptop as backrgound to my ultimatte 12 4K?

I tried it but it does not send any signal, I tried also connect camera as a background and it works.

Thank you for your help.
Stepan

[Ron Ungerman]

All Ultimatte products need to lock to the foreground input. So if you're using a PC, the output needs to match the input of the FG (foreground). The resolution and Frame rate need to match.