Finding Dates not working properly

[BrendanM]

I am a beginner to filemaker pro 10, and I am having difficulty narrowing my database by using the find function. I work at a gym and each morning we print out an active customer list who have paid up to 05/01/2009. When I used the find funtion in the "paid through" column, I searched greater than or equal to 05/01/2009. I made sure that the field type is set to "date". When I searched, only dates after 05/01/2009 appeared, however, a great deal of dates after 05/01/2009 did not appear that were left over from the clientelle list. Later I used the find function in the same column, searching with a question mark to find invalid dates, with a large amount showing up. Can anyone help me remedy this difficult problem so my database will list all date values within my search range?

[comment]

Hard to tell how to fix a problem, without knowing what the problem is. It depends on what makes those dates invalid.

[BrendanM]

I am unsure myself, however the database was created by all the same excel spreadsheet imported into filemaker. I believe the dates should all be the same format wise, so it is puzzling why such a large amount are invalid. I dont know if that clarifies anything with my problem but I appreciate the response

[comment]

Why don't you post a copy of the file, after deleting everything but the date field.