FTR 5.5.5 cartridge will not work with FMS 126.96.36.199.
There is a separate release of FTR 188.8.131.52 that works with FMS 184.108.40.206
Download the FTR 220.127.116.11 cart found in the below link.
Message when trying to activate the FTR 5.5.5 cartridge
Enabling the following cartridges will cause currently enabled incompatible/superseded cartridges to be disabled. Are you sure you want to proceed?