RadToolTipManager cannot find custom embedded skin, when a custom skin DLL is created with the Skins assembly builder (http://skinsassemblybuilder.telerik.com/).

Steps to reproduce:
1. Create a custom skin and wownload ZIP from Visual Style Builder (http://skinsassemblybuilder.telerik.com/)
2. Upload ZIP to Skins Assembly builder (http://skinsassemblybuilder.telerik.com/)
3. Create new project with Telerik template, turn off all options (like additional skins).
4. Add downloaded DLL as project reference.
5. Add to web.config:  <add key="Telerik.Skin" value="My_Skin" />
        <add key="Telerik.EnableEmbeddedSkins" value="true" />
        <add key="Telerik.EnableEmbeddedBaseStylesheet" value="true" />
        <add key="Telerik.Web.SkinsAssembly" value="My_Skin"/>
6. In Default.aspx, add
      <telerik:RadToolTipManager runat="server"></telerik:RadToolTipManager>

Result: an Internal Server Error is thrown:
Telerik.Web.UI.RadToolTipManager with ID='ctl03' was unable to find an embedded skin with the name 'My_Skin'. Please, make sure that the skin name is spelled correctly and that you have added a reference to the Telerik.Web.UI.Skins.dll assembly in your project. If you want to use a custom skin, set EnableEmbeddedSkins=false.

This behavior stops the user to be able o insert these elements without being tracked

When the Zip Skin archive is modified and uploaded to the SkinsAssemblyBuilder, the page throws a server error.