Baseband file Error rate calculation

Hi,

I am feeding a Baseband signal generated from Waveform generator app using Baseband File Reader block in Simulink. This BB signal is fed to ad9371 Tx. I would like to measure the error between Tx and Rx. When I am using Error Rate Calculation block in Simulink, there's a 100% error even though the constellation diagram is perfect. I would like to know how to calculate error in such a situation (using Baseband file reader).