blue tooth key board no pairing

Hi I have a problem with my key board old white one with mac mini 09 keyboard was working but not pairing

it will present a passcode to my mac mini but will not go beyond return, so I renamed it using a usb kb of course this was excepted but would not go past the return button so I have now tried it on my Imac and it says its connected and it sees the new name but no key functions also the green light on the rear gives two quick flashes with a pause any clues batterys are new.

I just had another look at this. The key board is used on my mac mini 06 using mountain lion, Its strange it just stopped working from one day to the next I can get it to work with the keyboard from my Imac so the blue tooth is working in the computer and the mouse is working! I have removed all the keyboards deleted and started a fresh still no joy as a final test I thought as it happends I am running a dual boot on this computer which has not been used for some time so I rebooted using a wired keyboard to see if I had the same isiue with a different operating system that previously worked ok,only to find I had the same problem.

Ihave also just tried it on my 09 mac mini that bolted on the rear of my TV as a media server and fails in the same way so it appears that the problem lies in the keyboard I have had a look inside and the ribbon cable is intact so it looks like i will have to bin it ! unless some else has a better solution?

Green light on the rear gives two quick flashes with a pause any clues batterys new seems to be only clue ,or is this normal?

Message was edited by: megger mac