Script Problems

[ExpectedIdentifier]

It's because you've written AddUseItemCallback as AddUseItemCallBack. Make the B lowercase and it'll work. And use this page from now on to make sure you get the syntax right:

Engine scripts [Frictional Game Wiki]


You need to understand the basics of how scripting works otherwise you're just going to keep running into these problems. I'd suggest reading some tutorials, there are loads linked on the page I just linked.