The DNN standard skins use TREEVIEW for their vertical menu skins. In the versions shipped in 4.8.2 Install they don't work. When you preview them they give the error message:

An error has occurred.
DotNetNuke.Services.Exceptions.ModuleLoadException:
Object reference not set to an instance of an object.
---> System.NullReferenceException: Object reference not set to an instance of an object.
at DotNetNuke.UI.Skins.Controls.TreeViewMenu.BuildTree(DNNNode objNode, Boolean blnPODRequest)
at DotNetNuke.UI.Skins.Controls.TreeViewMenu.Page_Load(Object sender, EventArgs e)
--- End of inner exception stack trace ---

Since the Install only includes Blue and Gray DNN skins, I took the yellow, green and red ones from the 3.1.1 archive. Their vertical menu versions work fine. I looked at the difference in the code, then added the missing code to the 4.8.2 version ones and now they work fine too.

Here is  the 4.8.2 code that fails:

<%@ Register TagPrefix="dnn" TagName="TREEVIEW" Src="~/Admin/Skins/TreeViewMenu.ascx" %>

    <TD class="leftpane" id="LeftPane" runat="server" valign="top" align="center">
      <dnn:TREEVIEW runat="server" id="dnnTREEVIEW" />
      <BR>
    </TD>

Here is the 3.1.1 code that works:

<%@ Register TagPrefix="dnn" TagName="TREEVIEW" Src="~/Admin/Skins/TreeViewMenu.ascx" %>

    <TD class="leftpane" id="LeftPane" runat="server" valign="top" align="center">
      <dnn:TREEVIEW runat="server" id="dnnTREEVIEW" 

       bodyCssClass="Normal" CssClass="TreeViewMenu" headerCssClass="TreeViewMenu_Header" 
       headerTextCssClass="Head" level="root" nowrap="true" treeIndentWidth="5" />
      <BR>
    </TD>

It seems that everything after id="dnnTREEVIEW" is missing in 4.8.2; maybe in earlier versions too.

 Is this a bug?

I have 4.9.1 installed, and the "missing" code mentioned above is in the skin file, but I still get the same error.  Anyone know of a solution?  By the way, my installation didn't seem to include the skin by default, so I downloaded it from dnnskins.codeplex.com.

Thanks.

Found the problem.  In 4.9.1, in Vertical Menu - Fixed Width.ascx, there is an error in the code:

<TD class="leftpane" id="leftpane" runat="server" valign="top" align="center">
      <dnn:TREEVIEW runat="server" id="dnnTREEVIEW" bodyCssClass="Normal" CssClass="TreeViewMenu" headerCssClass="TreeViewMenu_Header" headerTextCssClass="Head" level="root" nowrap="true" treeIndentWidth="5" />

id="leftpane" runat="server" should be removed.  Then it works fine.