Just to make sure, have you pressed the "Test" button in the bundle editor since you last changed your grammar? You have to press the "Test" button for TM to start using the changes you've made.
just pressed the 'test' button, and it's now working :-) Sorry to have made such a simple mistake!
I wonder whether the test button should be called 'activate' or other? I also wonder whether TextMate can detect if you've been playing with the bundle file, and inform you that the version you're looking at isn't currently activated, until you activate it.
Thanks for the help though! I guess I should just get on with my thesis though... it's that that really needs to be worked on! ;-)
Sam