[chrome] clicar numa opção Dinamica, não mostra Conteudo

[alfinete]

bom dia tenho aqui um site que tem construçãod e menus dinamica

esta a dar o seguinte erro quando clico num filho

     Uncaught TypeError: Cannot set properties of null (setting 'src')

quando clico nos pais abre o filho, quando clico no filho não abre o conteudo , Isto no Chrome
Agradecia uma juda

Js OnclickMenus
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function fncClickMenu(clickedMenuID, menuLevel)
{
    if(menuLevel == 1) menuPath = "";
    var containerObject = docElementByID(ControlPrefix + "containerMenu" + clickedMenuID);
    var parentObject = docElementByID(ControlPrefix + clickedMenuID);
    HideAllSubMenus(menuLevel);
    if(containerObject != null)
    {
        PositionObject(containerObject, parentObject);
        containerObject.style.visibility = "visible";
        if(menuLevel != 1) parentObject.className = 'menuItemSelected';
        if(menuPath.indexOf(clickedMenuID) == -1) menuPath += clickedMenuID;
    }
    else
    {
        HideAllSubMenus(1);
        if(parentObject.menuLink == '') return;
        
        if(parentObject.menuTarget == '_blank' || parentObject.menuTarget == '_new' || parentObject.menuTarget == '')
            window.open(parentObject.menuLink, parentObject.menuTarget);

            
        else
            document.getElementById(parentObject.menuTarget).src = parentObject.menuLink;
    }
}

c# generate Menus
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private HtmlGenericControl CreateDivControl(cMenuBE menuItem)
        {
            HtmlGenericControl localDiv = new HtmlGenericControl("div");
            localDiv.ID = menuItem.ID.ToString();
            localDiv.Attributes.Add("class",        menuItem.Level == 1 ? "menuTopLevel" : "menuItem");
            localDiv.Attributes.Add("onmouseout",   "SetHideTimeout()");
            localDiv.Attributes.Add("onmouseover",  "ClearHideTimeout()");
            localDiv.Attributes.Add("onclick",      "fncClickMenu('" + menuItem.ID + "', " + menuItem.Level.ToString() + ")");

            localDiv.Attributes.Add("menuLevel",    menuItem.Level.ToString());
            if (menuItem.Url.ToLower().StartsWith("http://"))
            {
                localDiv.Attributes.Add("menuLink", menuItem.Url);
            }
            else
            {
                if(menuItem.Url.Trim().Length > 0)
                    localDiv.Attributes.Add("menuLink", "http://" + Request.ServerVariables[37] + ":" + Request.ServerVariables[38] + "/" + menuItem.Url);
                else
                    localDiv.Attributes.Add("menuLink", menuItem.Url);
            }
            localDiv.Attributes.Add("menuTarget",   menuItem.Target);
            localDiv.InnerHtml = menuItem.Descr + (menuItem.Level > 1 && menuItem.HasChilds ? "    »" : "");

            return localDiv;
        }