Address #1 concerns "CosPhi regulator setpoint", which must be given a value between 60 and 100 - also if the regulator is not being used. Sometimes 0 is written to all addresses as default, which would conflict with this parameter, and this causes all other commands to be rejected as well.

Occasionally you must set bit 0 in the word you are writing to, to indicate you're writing to this address – otherwise the command for this word is ignored.