I have two spreadsheets and i am trying to do a HLOOKUP however i get a #N/A

The problem: They both have the date 10/1/07 but if i change the one date
to 9/30/03 it will do the look and when i change the dates to general, the
numbers match with the different dates but not if they are both 10/1/07.

Please help! Any solutions, what causes this?