I think I havefound a bug or solved the issue.
If I go to my live server then the shipping discount is saved and can bereloadedand edited however on my local test server it is not.
Possibly a permissions issue???
My test server is the 64bit version of wamp on a windows 7 64 bit machine.
I cant test the remote fully as I'm waiting for fasthosts to setup https on the domain.
I'll let you know how I get on