I did some additional testing and it appears that there is no connection to the target that I'm lasing and to which target my wingman aims for.
As far as my approach, I would lase a target (in this case a tank) and call to my wingman to attack my target, which did nothing. I then told them to attack ground targets and when there was only a few targets available it seems like they followed the laser, but once 12 targets are out there, it became a free for all.
I also found it interesting, that even with wingman set to expert, and loaded with 4 LGB, static tanks, they missed all of them.
As far as the laser code, I had everything set to 1688, but I'm going to trying and set my wingman up with 1687 to see if that will help or hurt.