" CDM 1550LS+ DP6 " here IS your first clue,
DP6 may be a after market, NOT Motorola, option, that uses a different software.
There is a version of the 1550LS+ that includes DP6 in the model number. The correct last 6 characters of the model number would be 9DP6AN which makes it a Passport and LTR radio with 160 LTR frequencies. If memory serves, that version can only do 16 conventional channels.
Regardless, it needs the Passport version of the CPS. It can not be programmed with the Conventional Professional Series CPS.
The region hack for the Conventional Professional Series CPS probably won't work on the Passport version.
The OP really hasn't given us much to go on. He should have provided the complete model number plus the full name and full version of the CPS that he is attempting to use. Since there is also an LA (Latin America and South America markets) version of the 1550's, the full model number is even more important.
FWIW, there are a number of previous discussions here on RR about the Passport version of the 1550LS+ that should answer most any question he has. Easily found with a tiny bit of a search.