Check your manual, PFI 10 may be an external timing line that affects all of your channels. Check your manual for details. Also, check the examples that ship with LabVIEW to look at the Digital Trigger examples to see if they can shed some light in the problem
If this doesn't show you the answers, post your code, and someone familiar with the hardware can take a look at it and see what might be going on.
Personally, I think you should look at the use of PFI 10. I don't have a manual for that board, so I don't know what that signal is, but I suspect it is probably the source of your problem.
-Michael Du'Lyea
Advanced Test Engineering
http://advancedtestengineering.com