Find Usages on "Using xxx=...;" doesn't seem to work

Hi,

when I have a class that states
using BE=OurCompany.Enterprise.BusinessEntities;

and I rightclick on BE and select Find Usages, it doesn't seem to find any usages.
But when I remove that line, I have several errors (on lines that do use that statement).

Anything you're working on or know about ?

Thanks for your insight.
Dirk