How do I fix the error I'm getting "the requested lookup key was not found in any active activation contex"?

Can you tell us the context of this error message? What are you running, what operating system are you running on.

There are a couple of things that this might be related to. I've read that this error sometimes pops up in Windows 7. Are you using that operating system? Second, this looks like it might be coming from a database query. Are you trying to run some sort of query? If so, what database, what software, etc?