LinqDataSource2.WhereParameters只能有效一次？

Question

  <asp:LinqDataSource ID="LinqDataSource2" runat="server"
                ContextTypeName="ProductReleaseDataContext" OrderBy="IATime desc"
                TableName="InquireAbout" Where="IAProductReleaseID == @IAProductReleaseID">
            </asp:LinqDataSource>
我设置了三个Button：
protected void Button1_Click(object sender, EventArgs e)
    {
        LinqDataSource2.WhereParameters.Add("IAProductReleaseID", TypeCode.Int32, "1");
        LinqDataSource2.DataBind();
        ListView2.DataSourceID = "LinqDataSource2";
        ListView2.DataBind();
    }
    protected void Button2_Click(object sender, EventArgs e)
    {
        LinqDataSource2.WhereParameters.Add("IAProductReleaseID", TypeCode.Int32, "14");
        LinqDataSource2.DataBind();
        ListView2.DataSourceID = "LinqDataSource2";
        ListView2.DataBind();
    }
    protected void Button3_Click(object sender, EventArgs e)
    {
        LinqDataSource2.WhereParameters.Add("IAProductReleaseID", TypeCode.Int32, "15");
        LinqDataSource2.DataBind();
        ListView2.DataSourceID = "LinqDataSource2";
        ListView2.DataBind();
    }
只有第一次有效果，后面按就没有效果了。怎么回事？我能怎么实现类似的功能？