Add this too to your code
dg1.DataBind()
Private Sub cmbdmidt_Leave(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmbdmidt.Leave
dg1.DataSource = Nothing
dg1.DataSource = GetData()
dg1.DataBind()
End Sub
or use
Private Sub cmbdmidt_Leave(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmbdmidt.Leave
dg1.DataSource = Nothing
dg1.DataSource = GetData()
dg1.DataMember="tablename"
End Sub
Hoping this will help you :)