Using NI 9205 module, external trigger into the PFI0 input.

I'm trying to put my external trigger into the PFI0 digital input.   When I connect up my hardware clock, it loads down my signal.  After putting a DC meter on the PFI0 line, open ckt, I see 1.85vDC just sitting there.   I have tried 2 different modules, and they show the same thing.   I am only looking at 1 chan input on AI1, and it is just a 5 volt level.