airport utility 5.6 does not recognize my password

Here's the deal. I have Airport Extreme and Airport Express. I moved our TV temporarily from the family room to the the guest room. The Airport Extreme is still in the family room next to the modem. Internet works fine for the computers. I have a Sony BD DVD player that allows access to Netflix. Outsmarting myself I remembered my Airport Express (called "extender" by Airport utility) so I connected the Sony to the Express thinking I could get Netflix like I did when it was with Airport Extreme. Patience, please. So I go to AD and I see a discussion that says I need Apple 5.6 in order for Extreme and Express to work together. Aha! Problem solved! Wrong. Airport Utility will not recognize my password for Airport. Other folks can come over and I give them the password and no problem. I am totally perplexed. Help, please.