Populate asp:dropdownlist with result from StoredProcedure

I have a form with some fields to take input from a user in order to generate a report.
I have a Start and End Date date range, which are parameters to a stored procedure to return the available values in an asp:dropdownlist, for clientname and clientid as the value field.
Eventually, I would like to retrieve the values from javascript calendar selections;
But for now, I would just like this code to work with hard-coded values.....
I hard-coded my start and end date as:  '01/01/2008' and '02/02/2009'.
Attached is my code; but the error is:
Procedure or function 'rsp_cc_clienttype' expects parameter '@startdate', which was not supplied.
But, when I step thru the debugger I set up the parameters correctly AND I think my syntax is correct.

Please Help-
John

Sub GetData()
            Dim ds As New DataSet
            Using da As New SqlClient.SqlDataAdapter("rsp_cc_clienttype", objConn)
                Dim myComm1 As New SqlCommand("rsp_cc_clienttype", objConn)
 
                myComm1.Parameters.Add("@startdate", SqlDbType.SmallDateTime, 6).Value = sdate
                myComm1.Parameters.Add("@enddate", SqlDbType.SmallDateTime, 6).Value = edate
 
                myComm1.CommandType = CommandType.StoredProcedure
 
                da.Fill(ds)
 
                myComm1.ExecuteNonQuery()
 
                'fill clients
                With ddClient
                    .Items.Clear()
                    .DataSource = ds.Tables(0)
                    .DataValueField = "clientid"
                    .DataTextField = "clientname"
                    .DataBind()
                End With
 
                If objConn.State <> ConnectionState.Closed Then
                    objConn.Close()
                End If
                'End Try
            End Using
        End Sub

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