[amsat-bb] ARISSat1/RADIOSCAF-B doppler in SatPC32 problem

I set up an entry in Doppler.sqf, originally as ISS and now as RADIOSCAF-B for the ARISSat1 CW and telemetry frequencies. SSB receive only so TX set to 0 MHz, step 20Hz. Unfortunately the doppler correction is not following the received frequency correctly. The rate of change is wrong so I lose lock on the telemetry decode after less than 1 minute. Any ideas as to what I have missed? Dick G4BBH