I have 2006 MB R 320 CDI. I installed an aftermarket trailer hitch with harness specified for r-class. Everything went well. The connector fits perfectly into the SAM, but trailer lights don't work. No power to socket. I found from internet there are fuses #70 and #72 at rear fuse box for the trailer, but in my car there are only 65 slots for fuses in the rear fuse box. I also read that relays K and U must be installed into the rear fuse box, but there is no slot for the relay U. Does anybody have a solution for this problem? Do I need to buy a new rear fuse box? Thank you in advance.