Date in DatePicker

[Tengkorak]

i have problem when display date data from database to display on DatePicker.
the error is:
"Conversion from string "30/08/2011" to type 'Date' is not valid."

this vb code:

dtPO.Value = CDate(dtt.Rows(0).Item("po_date"))

data in database is "30/08/2011", not error if data "07/04/2011"

at other pc this can run well.