Filter defects between two dates in QC

Hi ,

I am using below code for exporting defects from Quality Center between two dates. Code is given below -

BugFilter.Filter("BG_DETECTION_DATE") = "<=" & ActiveSheet.Cells(2, 4).Value & " And " & ">= ActiveSheet.Cells(2, 5).value"

Where as the values in xcel cells are

Cells(2, 4)= 4/1/2013

Cells(2, 5)= 4/22/2013

After running the code I am getting Below error

INVALID DATE FIELD VALUE

Kindly HELP.