Well, here's the rub I found. My reference to that library had the prefix tag of "SharePointWebControls." That's probably because it's in a Publishing site and so it give it a more descriptive name. Anyway, I was using that prefix and kept getting errors. Namely the "Object reference not set to the instance of an object" error.
I don't really see why changing the prefix from "SharePointWebControls" to "SharePoint" fixed it, but it did.
NOTE: You'll have to change everything with that prefix, so do a "replace all" or many things will break.
TANGENT: I don't know why I continue to post to MSDN Forums. I almost always answer my own questions when I do. I just keep going back in hopes something will change. I really need to stop. Is there some type of 12 step program to quit bad forums (BFA: Bad Forums Anonymous)?