KVM's and USB - PS2 Adapters: "Active" Doesn't Work Either

I'm using my third (obsolete, but widely available, and, yes, they keep breaking) Cybex - APC Commander KVM. This aging KVM design has no USB inputs. A new Dell 2900 server uses only USB keyboard and PS2 connectors. The inexpensive adapters that ship with new mice/keyboards didn't work. Some web research indicated that "active" adapters, with small circuits to bridge the two standards, might be more effective. I tried a pair sold by Sewell Direct. No dice.