Front passenger door problem, 94 Ford Escort

I recently got a 94 Ford Escort. The front passenger side door opens fine from the outside but will not open from the inside. This is very annoying to my passengers, as they cannot get out without rolling down the window and using the outer door handle! I keep wondering if there is some kind of childproof setting on the door, or if the inside door handle is broken. This is a manual lock, not automatic. Thanks for any advise you can give!