Error Message: TextBox

My data is like that:

I open the "Input" form
there 2 textboxes
search1 => Field name from Table
value1 => value from the table depend on search1 name

it is a filter.
And, this form has "Input_sub" form, because I want to do filter.

// this case is work well
Case1:
search1: Vendor Name
value1: Amy
//Do Again
search1: Date
value1: 8/31/2005
//Do Again
search1: Vendor Name
value1: Jimmy
...


// This case is Not OK, has error
// this one is OK
search1: Date
value1: 8/31/2005
// Do Again, Error come out
search1: Vendor Name
value1: Amy
//Error message appear
"The value you entered isn't valid for this field, For Example, you may have entered text in a numeric field or a number that is larger than the Fieldsize setting permits"

Please give me the direction to solve this problem. I tried many ways, it still be there. I ever change the Datatype of date to be Text of the "Input" Table, then it works, but I want to use datatype of Date to be Date/Time.

Please help.

Thanks. Thanks a lot.