Pivot Filtering by Dates

Hi,

I have a worksheet with a number of columns. two of these are dates and are formatted the same (as far as im aware).
I want to make pivot tables with other columns fields following on from these dates, so I created 1 pivot for Completion Due date and another for Completion Date, but when I try to filter by date, i can only do it by 'date' on the Completion Due Date field and 'value' on the Completion Date field.
I want them both to be filterable by date.
Do you know why i am unable to filter one by date when i can the other?

TIA

Please do not cross post without links. Read this to understand why.

http://www.excelforum.com/excel-general/1126413-pivot-filtering-by-date.html

Thanks for letting me know for next time. My apologies.