Hello Brian,
It will be difficult to provide useful advice without seeing your flowgraph. Does your file correctly get written if you bypass the actual radios and simply connect the transmitter and receiver flowgraphs together? If it does then you probably need to add synchronization to your receiver.
Another good check is to look at the received raw spectrum and ensure that the signal is being received at an appropriate power level. How do you have the two USRPs connected? Antennas or coax with an attenuator?