KVM Switch Will Not Switch

Ran into some problems with one KVM switch.
Couldn't switch between computers with Scroll lock, scroll lock and #.
Figured out that we had to shut down all the computers.
Then, and I don't know if all these steps are necessary but they worked, switch the KVM manually to the computer that you are booting until it boots up.
See if the KVM switch works with Scroll lock, scroll lock and #. Do it with each computer until you have all working. This worked with one Trendnet TK-400.