On Excel 2013 here.

1. I imported data from SQL into PowerPivot.
2. I have a datetime column, i.e.: "7/31/2013 2:03:51 PM"
3. I want to create a calculated column which converts that datetime to "of week" in mm/dd - mm/dd format, example for the above datetime: "7/28 - 8/3" as 7/31 fell within that week.

I don't know if there's a single formula to get this, I'm creating multiple calculated columns to get to the final result. I was able to create two new calculated datetime columns with the first day of that week, and the last day.
So for the above datetime I have 2 new datetime columns:
FirstDayofTheWeek: "7/38/2013 2:03:51 PM"
LastDayofTheWeek: "8/3/2013 2:03:51 PM"

The next step would be to use =MONTH and =DAY to extract the data to get a final column with nice "mm/dd - mm/dd" format right?

The problem:
If I try to execute a =MONTH or =DAY function on a calculated datetime column, PowerPivot errors:
"Calculation error in column 'Query 1'[]: An arument of function 'MONTH' has the wrong data type or the result is too large or too small."

The function I'm running to test this is a simple: =MONTH([FirstDayofTheWeek])

1. The FirstDayofTheWeek column is data type "date"
2. Same thing happens with the =DAY function
3. This works perfectly fine in Excel, but seems broken in PowerPivot
4. This also works fine on the original datetime column that was imported from SQL

Any ideas? Is there a completely easier way of doing this?