Can't Package Unreal Tournament Map

Hi all,
Not sure if this is the right place to post this problem, but I cannot package a CTF level I just built.
I keep getting the same error message over and over.
Someone on another forum suggested to build a blank map first, so I tried that and experienced the same error.

I might be overlooking something simple, I’ve been up all night trying to get this working.

Thanks in advance.