>> Unresolved External FINDLAST@F12STRINGTHEORYsblll
Unresolved External means that one thing is using another thing, and the other thing isn't there.
Figuring out what the "other thing" is in this case is simplified by the name...
(ie, it's StringTheory).
You need to refresh the StringTheory classes in your Data DLL, then work forward from there.