setting DefaultValue of UpdateParameter gives error

I'm using the following snippit of code to update an entry:

Protected Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles button1.Click
    With SqlDataSource1
        .UpdateParameters("id").DefaultValue = Request.QueryString("id")
        .UpdateParameters("pageContent").DefaultValue = edittor.Content
        .Update()
    End With
End Sub

The problem is that is says

.UpdateParameters("id").DefaultValue

Object reference not set to an instance of an object.

I've used it this way before (I think). Could somebo开发者_如何转开发dy please explain why this is messed up OR, because I've noticed that most people do it straight in the SQL, how to do this the correct way (i.e. updating an entry in my table).

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This is not the best solution but you can try this one. For this you should not include that parameter in .aspx page otherwise it will throw an error.

First Method:

Protected Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles button1.Click
           Dim id As New Parameter
        id.Direction = ParameterDirection.Input
        id.Name = "ID"
        id.DefaultValue = RubricID

        If SqlDataSource1.UpdateParameters.Contains(id) = True Or SqlDataSource1.UpdateParameters.Count = 1 Then
            SqlDataSource1.UpdateParameters.Item("ID").DefaultValue = RubricID
        Else
            SqlDataSource1.UpdateParameters.Add(id)
        End If
        SqlDataSource1.Update()     
End Sub

Second Method:

Specify parameters OnUpdating Event of SqlDataSource

   Protected Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles button1.Click
    SqlDataSource1.Update()   
    End Sub

Protected Sub SqlDataSource1_Updating(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.SqlDataSourceCommandEventArgs) Handles SqlDataSource1.Updating
       Dim ID = New SqlParameter("@ID", CType(Page.RouteData.Values("id"), Int16))
            e.Command.Parameters.Add(ID)
    End Sub