I cant enter Corsa keycode it wont let me?

I have the keycode for my stereo in my corsa on a little card from Vauxhall and have entered it before with no issues following the manual...........

This weekend i have changed the battery and went to follow the procedure for the keycode...

The display was not saying SAFE or what ever and it wont even let me enter the code..... I held the botton in and turned the radio on etc... but nothing..
The display just continues to say the date and time and temperature. nothing else..
PLEASE HELP !!!

Andy