Protected Sub GVZakazDetal_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles GVZakazDetal.RowDataBound
        Static rownum As Long =  0 
        Dim rval As String
        If e.Row.RowType = DataControlRowType.DataRow Then
            rownum +=  1 
            rval = e.Row.DataItem("OPERROWID").ToString
            e.Row.Attributes.Add("onmouseup", "letFromParent(" & rval & "," & rownum & " );")
        End If
    End Sub

<tr onmouseup= "letFromParent(334530,1 );" >
   <td>                        
        <input id="Detal" type="image" title="Нажмите чтобы выделить строку заказа." 
                  src="Picts/Sel1.gif"  
                  onclick = "return false;"  
                   нужно сюда   
                              />