I am feeding the CAL OUT (300 mHz -20 dBM) directly to the input of the First Converter, using the hardcable that normally connects to the output of the attenuator.
The HP-8594E is showing the signal level as -50 dBm.
If I attempt to run amplitude cal I get that same error message CALSIGNAL NOT FOUND
So, looks like my loss of gain is somewhere after the attenuator.