Disadvantages of radio advertising:
Misunderstanding: sometimes there might be a misconception regarding the radio ad as it is only heard. In television the chances of such misconception is less as it is audio as well as visual.
RJ needs training: it is very important that the Radio Jockey is trained enough to deliver the ad. Sometimes the voice really matters. If the voice is irritating then there is a chance that the campaign may flop.
No proper research available: no proper research has been available on the area of radio listening. So there could be a problem for the marketers in the sense that they might advertise on wrong channel at a wrong time.