Saving customized SDLToSQL10 throws an exception

I copied SDLToSQL10.tt from its home directory to my project directory for customization. Any time I save it, the following message is thrown:

Error 3 Running transformation: System.ArgumentNullException: Value cannot be null.
Parameter name: s
   at System.IO.StringReader..ctor(String s)
   at Microsoft.Data.Entity.Design.DatabaseGeneration.EdmExtension.CreateStoreItemCollection(String ssdl, Version targetFrameworkVersion, IList`1& edmErrors)
   at Microsoft.VisualStudio.TextTemplating7A31C00F77E544EFFE239DBD4801C2A8.GeneratedTextTransformation.InitializeAndValidateExistingStore() in c:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\Extensions\Microsoft\Entity Framework Tools\Templates\Includes\GenerateTSQL.Utility.ttinclude:line 61
   at Microsoft.VisualStudio.TextTemplating7A31C00F77E544EFFE239DBD4801C2A8.GeneratedTextTransformation.TransformText() in c:\Projects\trunk\InforFaaUser\InforFaaUser.Web\SSDLToSQL10Local.tt:line 232
   at Microsoft.VisualStudio.TextTemplating.TransformationRunner.RunTransformation(TemplateProcessingSession session, String source, ITextTemplatingEngineHost host, String& result)  1 1 

However, the script works just fine.

Thanks