Problem with shipping modules

[peewhy]

I'm in the UK and want to ship within UK.

I've added 'GB' in zone one but when I test an order, I get this message
"The shipping rate cannot be determined at this time "

Why won't it recognise GB...I've even tried GB,UK

I've set up UK in Modules and in Locations.

I also added a county (Hertfordshire) and ensured both Herfordshire and United Kingdom are in the test address but at the checkout point I still get the message
"The shipping rate cannot be determined at this time".

Any help would be appreciated!

[schoolboy]

Have you enabled (and configured) zone shipping module?

[peewhy]

I've done so many things, I've lost track...what do I need to do to configure and I'll re-check?

Thanks