三级联动选择值变化问题,来者有分!有点急,在线等
我现在用Datalist做了一个三级联动,但到了最后一个,它的值不会跟我选择的变化而变化?(我的意思是:     品牌(下拉)   系列(下拉)   具体某一个产品(下拉)   ;就在具体某一产品的时,它只默认最上面的一个,我选了其它产品,但它的ID值就是不变,是怎么回事)

源码如下:
private   void   Page_Load(object   sender,   System.EventArgs   e)
{
//   在此处放置用户代码以初始化页面
if(!IsPostBack)
{
ddlCategoryBind();

ddlCategory1Bind();
ddlCategory2Bind();

Label2.Text   =   ddlCategory2.SelectedValue;


}


}


private   void   ddlCategoryBind()
{
Db.Category   myCategory   =   new   Db.Category();

DataSet   ds   =   myCategory.dsCategoryDeepID4( "4 ");

ddlCategory.DataSource   =   ds.Tables[0].DefaultView;
ddlCategory.DataTextField   =   "Category ";
ddlCategory.DataValueField   =   "OrderID ";
ddlCategory.DataBind();
}

private   void   ddlCategory1Bind()
{
Db.Category   myCategory   =   new   Db.Category();

DataSet   ds   =   myCategory.dsCategoryFatherID4(ddlCategory.SelectedValue);

                                       

/*(能不能帮我解释一下这注释代码,谢谢 for(int   i=0;i <ds.Tables[0].Rows.Count;i++)
{
if(ds.Tables[0].Rows[i][2].ToString()== "001 ")
{
ds.Tables[0].Rows[i][3]   =   ds.Tables[0].Rows[i][3].ToString();
}
else
{
for(int   j=1;j <int.Parse(ds.Tables[0].Rows[i][2].ToString());j++)
{
ds.Tables[0].Rows[i][3]   =   "|__ "   +   ds.Tables[0].Rows[i][3].ToString();
}
}
}*/

ddlCategory1.DataSource   =   ds.Tables[0].DefaultView;
ddlCategory1.DataTextField   =   "Category ";
ddlCategory1.DataValueField   =   "OrderID ";
ddlCategory1.DataBind();
Label3.Text   =ddlCategory.SelectedValue;
}

private   void   ddlCategory2Bind()
{
Db.Category   myCategory   =   new   Db.Category();

DataSet   ds   =   myCategory.dsCategoryFatherID41(ddlCategory1.SelectedValue);




ddlCategory2.DataSource   =   ds.Tables[0].DefaultView;
ddlCategory2.DataTextField   =   "proname ";
ddlCategory2.DataValueField   =   "ID ";
ddlCategory2.DataBind();
Label1.Text   =   ddlCategory1.SelectedValue;

}



private   void   ddlCategory_SelectedIndexChanged(object   sender,   System.EventArgs   e)
{
ddlCategory1Bind();
}

private   void   ddlCategory1_SelectedIndexChanged(object   sender,   System.EventArgs   e)
{
ddlCategory2Bind();
}



#region   Web   窗体设计器生成的代码
override   protected   void   OnInit(EventArgs   e)
{
//
//   CODEGEN:   该调用是   ASP.NET   Web   窗体设计器所必需的。
//
InitializeComponent();
base.OnInit(e);
}

///   <summary>