GridView自定义分页（vb）

在用GridView里自带的分功能的时候，出现在一个有点奇怪的问题，点下面的页码，会执行上面按钮扭执行的动作，所以就用了一个自定义分页的功能。现将功能描述如下：
aspx页代码：

<%@ Page Language="VB" MasterPageFile="~/products.master" EnableEventValidation="false" AutoEventWireup="false" CodeFile="more_newproducts.aspx.vb" Inherits="more_newproducts" %>
<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
<table style="width: 576px">
<tr>
<td style="width: 576px">
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
DataKeyNames="productid" GridLines="Horizontal"
Width="576px" Font-Size="13px" HorizontalAlign="Center" CellPadding="0" AllowPaging="True">
<Columns>
<asp:TemplateField>
<ItemTemplate>
<asp:Image ID="Image1" runat="server" Height="80px" ImageUrl='<%# "~/upload/"+Eval("s_imgurl") %>'
Width="80px" BorderColor="Silver" BorderStyle="Double" BorderWidth="3px" />
</ItemTemplate>
<ItemStyle Width="90px" />
</asp:TemplateField>
<asp:TemplateField HeaderText="productid" InsertVisible="False" SortExpression="productid" Visible="False">
<ItemTemplate>
<asp:Label ID="lblproid" runat="server" Text='<%# Bind("productid") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="productname" SortExpression="productname" Visible="False">
<ItemTemplate>
<asp:Label ID="lblproname" runat="server" Text='<%# Bind("productname") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="物品名称">
<ItemStyle Width="206px" HorizontalAlign="Left" VerticalAlign="Middle" />
<ItemTemplate>
<asp:HyperLink ID="HyperLink1" runat="server" Font-Underline="False" NavigateUrl='<%# Eval("productid", "productdetailsinfo.aspx?productid={0}") %>'
Text='<%# Eval("productname") %>'></asp:HyperLink>
</ItemTemplate>
<HeaderStyle HorizontalAlign="Left" VerticalAlign="Middle" />
</asp:TemplateField>
<asp:BoundField DataField="pifajia" HeaderText="价格" SortExpression="pifajia" >
<ItemStyle Width="50px" HorizontalAlign="Center" VerticalAlign="Middle" />
<HeaderStyle HorizontalAlign="Center" VerticalAlign="Middle" />
</asp:BoundField>
<asp:BoundField DataField="pinpai" HeaderText="品牌" SortExpression="pinpai" >
<ItemStyle Width="60px" HorizontalAlign="Center" VerticalAlign="Middle" />
<HeaderStyle HorizontalAlign="Center" VerticalAlign="Middle" />
</asp:BoundField>
<asp:BoundField DataField="changdi" HeaderText="产地" SortExpression="changdi" >
<ItemStyle Width="70px" HorizontalAlign="Center" VerticalAlign="Middle" />
<HeaderStyle HorizontalAlign="Center" VerticalAlign="Middle" />
</asp:BoundField>
<asp:TemplateField>
<ItemTemplate>
<asp:Button ID="cart" runat="server" CommandName="cart" Text="buy" Width="40px" />
</ItemTemplate>
<ItemStyle Width="50px" HorizontalAlign="Center" VerticalAlign="Middle" />
</asp:TemplateField>
<asp:TemplateField>
<ItemTemplate>
<asp:Button ID="favorite" runat="server" CommandName="favorite" Text="收藏" Width="40px" />
</ItemTemplate>
<ItemStyle Width="50px" HorizontalAlign="Center" VerticalAlign="Middle" />
</asp:TemplateField>
</Columns>
<HeaderStyle BackColor="#507CD1" ForeColor="White" Height="22px" />
<PagerSettings Visible="False" />
</asp:GridView>
</td>
</tr>
<tr>
<td style=" font-size :13px" align ="center" >
<asp:LinkButton ID="btnFirst" CommandArgument="first" OnClick="PagerButtonClick" runat="server">首 页</asp:LinkButton>
<asp:LinkButton ID="btnPrev" CommandArgument="prev" OnClick="PagerButtonClick" runat="server">上一页</asp:LinkButton>
<asp:LinkButton ID="btnNext" CommandArgument="next" OnClick="PagerButtonClick" runat="server">下一页</asp:LinkButton>
<asp:LinkButton ID="btnLast" CommandArgument="last" OnClick="PagerButtonClick" runat="server">尾 页</asp:LinkButton>
<asp:Label ID="LblCurrentIndex" runat="server"></asp:Label>
<asp:Label ID="LblPageCount" runat="server"></asp:Label>
<asp:Label ID="LblRecordCount" runat="server"></asp:Label>
<asp:Label ID="LblNoRecord" runat="server" Text="记录为零" Visible="False"></asp:Label>
</td>
</tr>
</table>
</asp:Content>

aspx.vb代码：

Imports System.Data
Imports System.Data.SqlClient