extra side bars

Hi,
I’m adding unique sidebars to posts and so far I have added four which work well with posts. The idea is that I can add specific side bar content applicable to a post setting the sidebar option in the post controls.
All going well with first four but while I can add another side bar in theme options I can’t get this new one to hold widgets (maps – axl posts) nor can I display the side bar. the post shows a blank side bar.
I change the side bar on the post to a previous side bar and no problem that works fine.
I guess I’m missing something but 2 hours checking things out and I’m lost.
Any ideas most welcome.
Cheers
Ian