Trying to back up iPhone4 to iCloud

I have never backed up my phone to iCloud. When I go to <settings--iCloud--storage and backup--back up now> it shows to be backing up and says "estimating time remaining..." but doesn't give a time. I let it sit like this for two hours last night with no results. It is plugged into the wall. It is connected to Wi-Fi. It is locked. This morning it is doing the same thing. Does anyone know why it isn't backing up?