They are there, but you may have to adjust a few of your settings to see it. Click the following links -

BUY & SELL > Airplanes > Warbirds > Gas or Glow

Once you are there, check the tabs just above all the ads and click the "ALL AD TYPES" tab. You may be viewing a tab in which your ad is not located and this would solve your problem. If that is not it, post here and I'll give you other ideas of what can be done.