Hi dragondiver,
Your E Series DAQ's counter outputs can only be routed to certain PFI lines. You can check the routing table in NI-MAX: when you are looking at your device, click the "Device Routes" tab at the bottom and it will show you which inputs work with which outputs. I think what's going on is that you are trying to route the counter to a PFI line that doesn't work.
Looking at the table, I see that counter 0 works with PFI3 and 4. If you try to route it to 0, 1, or 2, you will get the error you're seeing.
Does this resolve the issue?
Julian R.
Applications Engineer
National Instruments