Problem with Campaign Missions
 

I've created a series of missions but they started out as single missions and I wanted to add them to a campaign. I changed the file extension to "mc" and added them to the campaign, but everytime I check it after creating it it has reduced the number of missions from 11 to 8 or sometimes 6. What is it that I'm doing wrong, or is it possible to convert single missions to campaign missions?

I think i had this problem trying to make a campaign once...
The problem was the file names included blank spaces, which i replaced with underscores, it was then fixed. Hope it is the same thing here;)

Cheers.