gvim error with rails.vim


I just installed Ubuntu 10.10 and vim 7.2.330.
I Use rails.vim and set it auto-start when pwd is rails directory.

vim works find.
However, gvim gives errors.

"Error detected while processing function <SNR>18_menuBufEnter.
E117: Unknown function rails#app
E15: Invalid expression: rails#app...
And some more error messages related to rails#app.

Why doesn't gvim work while vim works fine?
rails.vim is the latest, by the way.