Is the database getting updated when executing an action and your just don't see the answer from the server? or will the request never be send. You can find that out by looking at the logs/development.log file.
When you changed something in the tables (fieldnames, tablenames etc. ) I recomend to run the ajax scaffold generator again, if your not sure what needs to be changed - that may fix your errors. Attention on which files to overwrite.
you can read about the debuging stuff here: http://wiki.rubyonrails.com/rails/pages/HowtoDebugWithBreakpoint
And there something like a javascript debugger for firefox - but I don't know how it's called. ask google.
hope that helps
