Ads are placed on the regional ad boards, not the regional discussion boards. If you placed it on the discussion board, of course it will be rejected.

If you initially posted it on a regional ad board, and it was rejected, then there was another reason, but I can't imagine they told you that your ad had to be on a non ad board. Maybe you posted it on the wrong ad board and they told you to put it on another regional ad board, but they wouldn't tell you to put it on a discussion board. If you read and follow the rules under the "provider ad posting guidelines" your ad should post. The rules are not very hard to understand but they must be followed.

I don't know why anyone would tell you just the opposite of what you are supposed to do, unless they wanted you to fail.  You post ads on the regional AD boards, that's why they are called that.  Read the self help center, there is a section in there with the rules for posting ads.  

Be careful posting on the regional board, because if your post fits the TER ad guidelines, it will be rejected by Admin, which is what happened to you.

Swim

some months ago.  Has it been a year yet?  Who ever told you to use the local board misspoke  or hadn't been on in a while of might have even figured it was so obvious that you'd know.  (Or maybe being s sarcastic wise-guy.)  Often misplaced posts get reported & moved to the correct location.  
Well, now you know.