This is one of those rare cases where both the Name and FullName properties of an EnvDTE.CodeElement can return an exception “by design”!:

PRB: FullName and Name properties of EnvDTE.CodeElement return exceptions for using/Imports statements of C# and VB.NET
http://www.mztools.com/articles/2011/MZ2011013.aspx

Fortunately, there is an easy workaround.