GridView的分页问题（谢谢！）

this.Button1.Enabled = true;
        if (this.GridView1.PageIndex == 0)
        {
            this.Button1.Enabled = false;
        }
 protected void Button1_Click(object sender, EventArgs e)//上一页
    {
            this.GridView1.PageIndex = this.GridView1.PageIndex - 1;
            this.binding();
    }
protected void Button2_Click(object sender, EventArgs e)下一页
    {
        if (this.GridView1.PageCount > this.GridView1.PageIndex)
        {
            this.GridView1.PageIndex = this.GridView1.PageIndex+ 1;
            this.binding();//绑定
        }
        if (this.GridView1.PageCount == this.GridView1.PageIndex + 1)
        {
            this.Button2.Enabled = false;
        }
    }
为什么Button2的对着，点击Button1的时候不起作用？？