Pivot Table (from external source) not showing values

Hi guys,

There's this problem, a weird and crazy one, and I just can't seem to understand why or how to fix it.

Basically I have a table set-up in Excel 2010 for data entry (I attached the file here, Book1, I've deleted some of the fields. I left the entry form/macros in just in case it has something to do with the problem). Now one of the columns have a field named "Shift" which contains the values of either 1, 2, 3, 4, 1P, 2P, 3P, or 4P.

If I create a pivot table in the SAME excel workbook, everything works great, life is good. But when I create a pivot table in another new workbook, and link the data source connection to the Book1 sheet1, the "Shift" values will not show up correctly in the pivot table. It turns out that all the "1P, 2P, 3P, 4P" values are showing up as (BLANK) in the pivot table. If I double click the values in the (BLANK) cell, the table that is brought up contains actual blank values for the "Shift" Column. But in the original table in Book1, there are no blank values at all.

Any help would be greatly appreciated, thanks very much.