序时簙插件自定义参数获取不到

声明一列表，然后传入自定义参数，列表初始化时，自定义参数获取不到，代码如下： 单据插件里：
ListShowParameter showParamorder = new ListShowParameter();
showParamorder.FormId = "X";

showParamorder.CustomParams.Add("membercustparam", "1");

this.View.ShowForm(showParamorder);

对应列表的插件：
public override void PrepareFilterParameter(Kingdee.BOS.Core.List.PlugIn.Args.FilterArgs e)
{
base.PrepareFilterParameter(e);
memberfilter = this.ListView.OpenParameter.GetCustomParameter("customparam").ToString();
membercustparam = this.ListView.OpenParameter.GetCustomParameter("customparam").ToString();
if (membercustparam.Equals("1"))
{
e.FilterString = "";
e.AppendQueryFilter(membercustparam);
}
}
获取自定义参数时，找不到对应的键值