aspxgridview CustomButtonCallback 不支持弹出消息提示解决方法

protected void ASPxGridView1_CustomButtonCallback(object sender, ASPxGridViewCustomButtonCallbackEventArgs e)
{
ASPxGridView view = sender as ASPxGridView;
if (e.ButtonID == "btnAudit")
{
int id = 0;
int.TryParse(view.GetRowValues(e.VisibleIndex, "id").ToString(), out id);
if (true)
{
view.JSProperties["cpErrorMsg"] = "审核成功！";
view.DataBind();
}
else
{
view.JSProperties["cpErrorMsg"] = "此单据已经审核！";
}
}
}

function EndCallBack(s, e) {
if (s.cpErrorMsg!="") {
alert(s.cpErrorMsg);
}
}