How do I change the category of an ad in Classifieds?

[Bingley]

Last week I posted an ad in Classifieds that included a lens and a Canon P camera body. I put the ad in the lenses category in Classifieds. The lens has sold, and now I'd like to move the ad to the 35mm cameras category, but that's not an option I see when I edit the ad. Is there a way to do this?