Vectra B (2001) keyfob not working

[woz71]

Hi ! my spare keyfob has stopped working ! the light on the fob flashes when i press either button the first time but if i press it again it doesnt flash ( if i wait another minute or so it will again flash on the first press ) i initially thought it must be the battery so i changed it for a new one but same result , the key will start the engine but the fob will not operate the central locking , ( i have 2 vectras and the same has happened to the spare key ) do you guys (or gals ) have any ideas ,
ps the main keyfob works everything fine it just the spare

[Dom]

Sit in car
Turn on ignition
Press keyfob button within 30 seconds

As for the flashing light, sounds like either you've been unlucky and put in another duff battery or the battery terminals are loose or have come away from the PCB.