>Can you look at the exact command being sent from .NET? Fire up SQL Profiler before executing your code.

This is my test environment:

exec sp_executesql N'SELECT Numero FROM Admin WHERE Admin.EmailName=@EmailName ',N'@EmailName nvarchar(40)',@EmailName=N'Michel′Fournier      '

Between Michel and Fournier, there is the Prime character. I can see in the SQL Profiler that this is being displayed as a square box meaning that it cannot display it.

In the SQL Profiler, we can see that it uses the N syntax for the value. Do you see anything wrong in there?