I recently migrated my PPC campaigns over from Yahoo to Microsoft Adcenter as part of the new bing / yahoo search alliance.
But I've noticed a big drop in impressions on Adcenter for the same campaigns that were running on Yahoo.
I've since returned to Yahoo and turned on my original campaigns and they're back to normal with higher impressions & clicks.
Does anyone know whats going on here? the Adcenter ads are meant to be covering both Bing and Yahoo search and should provide even more impressions but something is clearly wrong and I can't see where the problem lies.
Any help would be great as the required switch over is coming soon.