Did you put the ads on your site a today or a few days ago? because usually it will take a few days before the ads are showing.
I also experienced this but now everything is ok. Try to change the category or just wait a few days - as Arkserver said.
my content is about proxy. and I have another site which used bidvertiser for a month, but it always shows your free ad here. did this because there's little ad in this category？ it showed ads yesterday. but just for only one day or less.
Dump them and try an alternative like adbrite if they can't deliver any ads to your category or site.
Have you selected to approve your adds before displaying? Maybe thay are all pending your aproval? MONEYSAVER.
bidvertaiser allways like that..... they never pay money if payment date comes that time they will tell, all clicks are invalid... dont waste your time on that bullshit company try adsense....... you will get something.....
thats one reason why i hate bidvertise too...very cheap site targeting..i get Poker ads on my site about environment preservation!!! wth lol