Yahoo launches APT ad-buying tool, confuses agency friendsYahoo's marketing department didn't like "Apex," and their choice, AMP, was already taken, so when Yahoo finally announced its new display advertising dashboard for sales representatives yesterday, the company decided to call it APT. The San Francisco Chronicle and the San Jose Mercury News have already signed up, reports the Wall Street Journal. Yahoo's friends at ad agencies Publicis, WPP and Havas plan to hold off on using it, though.Mostly because each has already announced plans to develop dashboards of their own — in partnership with Yahoo — and they're confused about the new tool. "For us, we've already got something going with Yahoo, and I'm not sure this changes that strategy," one agency exec told the WSJ. "The news is more a continued statement along the line that digital media is really hard to buy. We need to make it easier."