datalist分页


.aspx页面
<table>
                    <tr>
                        <td style="width: 66px">
                            <asp:Label ID="Label2" runat="server" Text="当前页："></asp:Label>
                        </td>
                         <td style="width: 13px">
                            <asp:Label ID="currentPage" runat="server" Text="1"></asp:Label>
                        </td>
                        <td style="width: 66px">
                            <asp:Label ID="Label3" runat="server" Text="总页数："></asp:Label>
                        </td>
                        <td style="width: 13px">
                            <asp:Label ID="totalPage" runat="server"></asp:Label>
                        </td>
                        <td style="width:71px; text-align: right; font-size: 12px">
                            <asp:LinkButton ID="firstPage" runat="server" onclick="firstPage_Click" >首页</asp:LinkButton>
                        </td>
                        <td style="width:71px; text-align: right; font-size: 12px">
                            <asp:LinkButton ID="fontPage" runat="server" onclick="fontPage_Click">上一页</asp:LinkButton>
                        </td>
                        <td style="width:71px; text-align: right; font-size: 12px">
                            <asp:LinkButton ID="nextPage" runat="server" onclick="nextPage_Click" >下一页</asp:LinkButton>
                        </td>
                        <td style="width:71px; text-align: right; font-size: 12px">
                            <asp:LinkButton ID="lastPage" runat="server" onclick="lastPage_Click" >尾页</asp:LinkButton>
                        </td>
                        <td style="width: 71px">
                         转到第 
                            <asp:DropDownList ID="DropDownList1" runat="server" 
                                onselectedindexchanged="DropDownList1_SelectedIndexChanged">
                            </asp:DropDownList>
                           页
                        </td>
                    </tr>
                </table>.cs页面
    static PagedDataSource pds = new PagedDataSource(); 
   
    public void Bind()
    { 
        string s = Request.QueryString["keyword"];
        SqlDataAdapter da = new SqlDataAdapter();
        da.SelectCommand=new SqlCommand ("select * from A where ATitle like '%" +s + "%' or AContent like '%" + s + "%' order by AId desc",conn);
        DataSet ds = new DataSet();
        try
        {
            conn.Open();
            da.Fill(ds, "a");
            int count = ds.Tables["a"].Rows.Count;
            this.labMsg.Text = "搜索到：" + count + " 条记录！";
            conn.Close();
        }
        catch (SqlException el)
        {
            Response.Write(el.ToString());
        }
        int cur = Convert.ToInt32(currentPage.Text);//当前页数，初始化为第一页
        pds.DataSource = ds.Tables["a"].DefaultView;
        pds.AllowPaging = true;
        pds.PageSize = 5;
        pds.CurrentPageIndex = cur - 1;
        int countPage = int.Parse(pds.PageCount.ToString());
        totalPage.Text = countPage.ToString(); //获取总页数
        if(!IsPostBack)
        {
            for(int i=1;i<pds.PageCount+1;i++)
            {
                this.DropDownList1.Items.Add(i.ToString());
            }
            fontPage.Enabled=true;
            nextPage.Enabled=true;
        }
        try{
            DropDownList1.SelectedItem.Text=cur.ToString();
            dlNews.DataSource=pds;
            dlNews.DataBind();
        }
        catch(Exception ex)
        {
           Response.Write(ex.Message);
        }
    }
    
    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)//跳转到指定页码
    {
        int page=Convert.ToInt16((DropDownList1.SelectedItem.Value));
        currentPage.Text = page.ToString();
        Bind();
    }
    protected void  firstPage_Click(object sender, EventArgs e) //第一页
    {
        if (currentPage.Text != "1")
        {
            currentPage.Text = "1";
        }
        else
        { 
            Response.Write("<script language=javascript>alert(\"已经是第一页\")" + "</script>");
        }
        Bind();
    }
    protected void  fontPage_Click(object sender, EventArgs e)  //上一页
    {
        try
        {
            if (Convert.ToInt16(currentPage.Text) > 1)
            {
                currentPage.Text = Convert.ToString(Convert.ToInt32(currentPage.Text) - 1);
                DropDownList1.SelectedValue = currentPage.Text;
                Bind();
            }
            else
            {
                
                Response.Write("<script language=javascript>alert(\"已经是第一页\")" + "</script>");
            }
        }
        catch
        {
            Response.Write("<script language=javascript>alert(\"已经是第一页\")" + "</script>");
        }
    }
    protected void  nextPage_Click(object sender, EventArgs e)  //下一页
    {
        try
        { 
currentPage.Text=Convert.ToString(Convert.ToInt32(currentPage.Text)+1);
            DropDownList1.SelectedValue=currentPage.Text;
            Bind();
        }
        catch{
            Response.Write("<script language=javascript>alert(\"已经是最后一页\")" + "</script>");
            currentPage.Text="1";
            Bind();
        }
    }
    protected void  lastPage_Click(object sender, EventArgs e)  //尾页
    {
        if (currentPage.Text.ToString() != totalPage.ToString())
        {
            currentPage.Text = totalPage.Text.ToString();        }
        else
        {
           
            Response.Write("<script language=javascript>alert(\"已经是最后一页\")" + "</script>");
        }
        Bind();
    }
这是一个搜索功能，搜索结果在控件datalist中显示，分页时出现下列错误：
比如：搜索结果一共两页，点击下一页（也就是到第二页）后，仍然可以继续点击下一页按钮，当前页显示为3。另外，dropdownlist1中选择页码也不能跳转到相应的页面中？不知道为什么，请教高手指点一下哪里有错误！急！！谢谢！