DAQ assistant - External clock

I'm using PCI-6111 to sample a 2MHz signal. I'd like to sychronize the DAQ with the function generator via the 10MHz reference clock from the function generator. I set the sampling rate to 5M, connected the function generator 10MHz ref output to PFI0 and set the "advanced timing" to "external" and "PFI0". However I get a DAQ assistant error 200284 saying that the samples haven't been acquired (even when the timeout is very long). 

Is it possible to achieve the sychronization I want? 

Thanks, 

Adi