I already had an objective. I'm only hunting midget subs just outside of Pearl, so I had set just a 1-ton limit to test with. I've since upped that; still quits. I changed the objective to units and specified the midget subs, then made the units 2 (the total currently in the mission); still quits after a few seconds.
I'm somewhat familiar with the SH3 builder and don't see much difference in SH4. I had already downloaded the pdf user manual from the link suggested. I don't see where I'm doing anything different than it states.
Still, I just put in patch 1.3 (the mission was created after that). Maybe it is involved, but I think I'm just overlooking something.
Can I post the mission text here and get comments?