Since early October, Google has been struggling to nail down the issue with their AdWords API reporting features.
A Google Groups thread reports that the API is returning reporting data either extremely slowly or not at all.
AdWords API Advisor has been addressing API user's worries throughout the thread. But yesterday said, "We do hope to have everything fixed very soon."
Upgrading to a new version of the API will not help, this is not version specific. You simply need to wait and see when Google fixes the API reporting issues.
Forum discussion at Google Groups.
Update: The API report delays should now be resolved. On November 12th, AdWords API Advisor updated the thread to confirm the issues should be resolved:
This should now be resolved.
Are you still running into problems with reports failing unexpectedly?
Cheers, -Jeff Posnick, AdWords API Team