The permissions appear to be correct. When the edit box shows up after clicking the Edit Post link there should be a button labeled "Edit Post" next to a reason text box, assuming the post is younger than the editing time limit of 30 minutes. This button is the submit button. Could you verify this for me? Unfortunately I'm not in a position to adjust my permissions status to test.
I just tried with my test account and I was able to edit a post I just created regardless of the forum. It worked for me here in this forum. The one thing I did notice is I needed to refresh the page after initially posting for the edit post link to appear, since the post initially appears with AJAX.
AD, are you sure that the reason it works for you in one forum but not the other is because you didn't realize your 30 minutes had expired in this forum?