Weird Mongoose. I get crap from findOne's doc.
Not really sure what's happening, but I'd first try a UserModel.find({}); Do this to see what, if anything, returns. If nothing returns you have a problem.
Also, one issue I've seen is that Mongoose is case sensitive. Make sure 'userId' is not supposed to be something like 'userid.' Command line will work (as far as I've seen) with the wrong case. Mongoose / Node will not.