Fast Template woes

Hey all, I got a rather strange probelm with fast template, I won't go into great detail unless someone has had a simular experience while using define_dynamic. Basically I have written a site which totally uses Fast Templates and some sections use define_dynamic which work perfectly, my problem is I have just added a new section which refuses to acknowledge the: <!-- BEGIN DYNAMIC BLOCK: handle_name --> <!-- END DYNAMIC BLOCK: handle_name --> tags (they appear in the final output) I have read all the documentation and am really sure that I have done this correctly, even checked the other pages which *are* working, no matter what I do this refuses to work, has anyone else run into a simular problem? Any help would be mutch appreciated, I am really stuck on this. Regards, Joseph