Heh, abomb tried to, but it was walker who really responded to your post.
CE2 uses the usermarker system. How this works is that in single player, user-added markers are numbered in sequence with the already-extant markers.
In other words, the usermarker system can only detect new markers being laid down if you tell it the exact number of predefined markers. So count them up, set the variable rPreGameMarkers to the appropriate number, and see if it works.
If you still have problems let me know.
The mission sounds cool. I developed my artillery simulator (which I'm adapting to CE format) after reading Hal Moore's account of fire support from LZ Falcon in the Ia Drang Valley battles. It was clear from his account that what his FO was doing was cool, but of a level of complexity beyond what he was able to fathom. I've written the simulator for that level of complexity; now I have to adapt it for all the virtual Col. Moores.
Anyway, I'd be happy to look at anything you've got. I'm an avid player of Combat Mission, and like to describe what we're doing as making a hybrid between the FPS of OFP and the strategic environment of CM.