Okay, did as suggested.

Followed track 271 out of 27 L and just after 3000 ft engaged as suggested, and the plane headed towards HDG 181 and just stayed there. Did not even make an attempt to head towards SAM, etc, etc.Stayed on 181 all the way to the Northern headland of Spain.

At that junction, I just gave up, and quit

I just cannot figure what it is I am doing wrong, or maybe I should give up INS-equipped aircraft as a bad joke. It was never like this with the 707 in FSX way back when.