Edit form Delete button doesn't work

I am using content type "comment" for the comments. when i review comments that users have left on my nodes i would like to edit and delete them. when i use form of editing the comment (like editing usual node) the button Delete doesn't work (after i click it i am redirected to the page where this comment is attached). i can delete the comments using link "delete" when i preview the comment. please advise if me only have this problem or this is designed this way? thank you.