Peugeot key fob

Help! On my key fob I can press the "open" button and the doors open but it does not lock when I press the "close" button. I recently changed the battery. Anyone know what the problem could be please?

You may have to reprogram the remote fob. Various procedures which vary by year and model can be found on G**gle or there may be instructions in your handbook.

Thanks Roger. Useful information.

I don't have a problem at  the moment, but I wasn't aware the fob could be user re-programmed. (I know - RTFM!! )

I did read somewhere that it might need it after battery change especially if more than 10 mins delay before fitting new one.
Shouldn't need the red master key, I think that should only be required for immobiliser reset.