eBay's plans to create an online television ad sales market seems to be faltering as the Cabletelevision Advertising Bureau said Thursday that it would no longer participate in the auction site's trial.

"We appreciated the opportunity to test the system - throughout our review it became apparent that the Media Exchange was too narrow an application, had clear connectivity issues related to cable's emerging end-to-end e-business platforms and lacked the provisions necessary for capturing critical strategic and idea-driven intelligence during a buy," CAB president and CEO Sean Cunningham said.

Called the eMedia exchange, the project was devised through the cooperation of about ten major advertisers and eBay. The loss of the CAB means there is no place for the ads to be shown, creating a serious problem for the service.

It also calls into question whether a similar effort by Google would be able to take off either. While the search giant has signed DISH Network onto the test, reception to the plan has generally been cool as well.

Central to the argument against both services, it seems, is the fact that there is no middleman, or person to negotiate better rates. In addition, there is nothing in place that would allow marketing to be integrated across other platforms.

eBay said it was disappointed with the decision, although added it would continue to press on and hoped to find another outlet through which to sell ad time. However, considering Google's struggles, that could be a very hard sell.