Excel PowerPivot import is not displaying 2013 data by week anymore

[DigitalRhoads]

We use a PowerPivot table to import website data to a large workbook. On the main report tab, the information is broken out by "Year" and then by "Week" (1-53). When 2013 began (and 2013 data was imported), the year 2013 automatically appeared on the reports, BUT this data is no longer broken out by week. The data is just aggregate totals for the year. As we import new data each week, the 2013 aggregate grows, but the data is not listed out by week for 2013. All fistorical data for 2008-2012 is still broken out by week appropriately.
How do I get 2013 to show data by week again?
Thanks on advance for any help!

 

[Laurent C]

Does the week still appear in the pivot table? Did your date table change? ...

 

[DigitalRhoads]

Does the week still appear in the pivot table? Did your date table change? ...

Nothing has been changed. The weeks still appear in the Pivot Table and all data prior to 2013 is still displayed by week (which we feel is odd considering each 'refresh' imports ALL historical data, not just the new data). Everything for 2008-2012 lists out by week collapsible by year, then 2013 just displays an aggregate total for the year - no breakout by week. Same format for imported data, no modification of the pivot table, merely a new year.
Thanks!

 

[Laurent C]

What measures do you have in said report? How is this measure defined? How do the data in the Week column look like for the year 2013?