Help!!! X5 trailer wiring harness question/Trailer Hitch Warning

[C4sF80M3]

I'm trying to finalize my trailer wiring harness installation; however, I'm having a few issues I'm trying to troubleshoot.

I was using the harness installation writeup for the invisihitch as my guide, but when it got to the last wiring section for plugging into the fuse box, one wire color didn't align exactly with what comes in the BMW harness.

For example, the first "Black" wire in the diagram does not exist. However, I do have a Red w/Blue wire that is not on their diagram. So I assumed this is the "Black" wire they are reffering to, but I could be wrong. So I plugged the wire into this location. Any guidance around this? What's the best way to confirm the installation of the wires?

Also, after coding in the controller, I keep getting a Trailer Hitch warning error, but I'm not sure if this is a coding issue, or just a wiring issue. Any suggestions are appreciated!!!