Welcome to the site. There can be many reasons for what you describe, so it is nearly impossible to know why.
In general, my advice is to start with just one change at a time. Start with a mission.lvl mod, just putting a different unit into a stock map. If that works--then take the next steps.
Some items you can include in a follow up post:
-what version of SWBF2 are you using (steam/GoG/DVD) and actual version number if you can find it
-your OS version (i.e. Windows 10, etc.)
-the path of your game (folder location)
-the link to the mod tools you are using
I will add more if I can think of more later.
In general, my advice is to start with just one change at a time. Start with a mission.lvl mod, just putting a different unit into a stock map. If that works--then take the next steps.
Some items you can include in a follow up post:
-what version of SWBF2 are you using (steam/GoG/DVD) and actual version number if you can find it
-your OS version (i.e. Windows 10, etc.)
-the path of your game (folder location)
-the link to the mod tools you are using
I will add more if I can think of more later.
