paging of gridview

我有一个允许分页的网格视图。但当我点击第二页时，网格视图消失了这是c#代码：

protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        GridView1.PageIndex = e.NewPageIndex;
        OdbcDataAdapter adpState = new OdbcDataAdapter("SELECT CALL_NO,TDATE,
        ID_NO,NAME,CONTACT,DEPARTMENT,ISSUE,STATUS FROM TBL_ITHELPDESK 
        WHERE (STATUS IS NULL OR STATUS <> 'CLOSED') AND  TDATE= TO_DATE('" +
          txtDate.Text.ToString().Trim() + "','MM-DD-YYYY')", con1);
        DataSet ds = new DataSet();
        adpState.Fill(ds);
        GridView1.DataSource = ds;
        GridView1.DataBind();    
    }

有人能帮我找出哪里出了问题吗