problem when i date RecordSelectionFormula ??

[xray]

peace be with you

i try to write to " RecordSelectionFormula " like this :

ex:
report.RecordSelectionFormula = "{tests.test_res1}='" + report_for + "'

-- this Formula bring me all data that "" = "" to report_for

***when i add this code for the Formula like this
ex :
report.RecordSelectionFormula = "{tests.test_res1}='" + report_for + "'"
report.RecordSelectionFormula = "{tests.test_date_med_wig}='#01/07/2006#'"

and error raise said (("" date-time is required here "" ))

how i can made a Formula to get the data that equal to special date ????