If you are an advertisers on Microsoft's Live.com adCenter, and you noticed your reports not being updated, you are not alone. A WebmasterWorld thread has details of adCenter reports not updating since 7:00 am EST on February 11th.
adCenter411, the official Microsoft representative confirmed the issue saying:
I just got word that because of the adCenter maintenance this past Saturday, reporting is behind. It may take a couple days for the data to be up to date - I will keep you posted as I learn more, including the expected resolution time for this. Thank you for your patience, adCenter411
So don't be alarmed if you see no data in your reports.
Forum discussion at WebmasterWorld.
