There are reports in the Google AdWords API Google Groups that the Google AdWords API is reporting inaccurate data from the usage tool.
First reports came in on March 19th, where an AdWords API user said:
We have just rolled out an application using API and the Unit Usage from 3 days ago is not showing up. It says on the page where this is viewed that it is updated daily. Anyone know whats going on there? Have we not been charged?
In short, Google charges for certain level of usage for the API. AdWords API users keep track of their usage reporting to stay on top of costs. The usage reporting seems to not be updating correctly and costs are hard to control without that reporting.
Jeff Posnick from the Google AdWords API Team said:
I have a bug open with the engineering team to determine whether there was some underlying problem that prevented the display in the web interface from being updated. Hopefully if there is a problem we can get it resolved so that no further confusion ensues.
Forum discussion at Google Groups.
