uncommenting a commented region leaves it commented in latex (auctex)

[Micha Feigin]

When I try to uncomment a region in LaTex-mode (auctex) using
tex-un-comment-region when the region was previously commented with
tex-comment-region doesn't return to the previous state.
tex-comment-region adds %%
and tex-un-comment-region removes only one %.
uncomment-region seems to do the right job.
Where do I fix this? (its emacs-bidi with auctex from debian unstable).