Presta or Schrader valve stem? If presta, are you loosening the stem and "burping" the tube so pressure can get into it? I have one tube on one of my bikes that seems to have a "sticky" core (presta) that I often have to burp 3 times before the core will let air into the tube. What you're describing sounds very similar. If that's not it, maybe the chuck is faulty. They are replaceable.