I know I have a few grey hairs because of addon weirdness. Macguba helped me out tho ;D .
I overlooked the addon requirments of the intro and outro.
Also, some addons have effects or objects that you might not associate with the addon.
For example:
(insert long boring story here)
I was using BAS MH47 while making a mission. I decided not to use it, but the mission kept on asking for it. I cleaned out the sqm over and over again--no help. I pasted my mission contenets onto a clean map--no help. I even reinstalled OFP --no help. Finally, I started deleting each object type, one by one. First went all vehicles, then all men units ( except for a standard soldier for player).Then went the emptyobjects and I found it--it was "RED GLOW WITH SMOKE" . What in the world does a red glow have to do with anything :hmm: ?! I then came to realize that the MH47 comes with red, blue, green, and yellow glows. I just assumed it was part of OFP and never associated it with the MH47.
BTW the BAS MH47 rocks!