I am trying to modify a skin that I really like to include the path to the currently selected tab. I have modified the ascx file to include the following line:

<td valign="bottom" align="center" bgcolor="black"><dnn:Breadcrumb runat="server" id="dnnBreadcrumb" /></td>

When I try to view the skin with the change I get the error: <b>Parser Error: Unknown server tag 'dnn:Breadcrumb'.

I have tried it with varying cases: lower case, upper case, mixed (dnn:BreadCrumb, dnn:BREADCRUMB, dnn:Breadcrumb)

Anybody know how I can fix this?

This error is occurring because you are most likely missing the Register tag for the control:

<%@ Register TagPrefix="dnn" TagName="BreadCrumb" Src="~/admin/Skins/BreadCrumb.ascx"%>

Adding the above line to your skin .ascx file will do the trick.

Nik