Why Does This Code Not Execute In Current Db?

I am creating a stored procedure to generate the sp_addrolemember syntax, since SQL 2005 does not script role members. The stored procedure is named sp_ so it can be executed from any database. However, any reference to a view beginning with sys. only gets executed in the master database and not the current database. Why?

Try this code for a test.

Use Master

GO

Create Procedure sp_test as
Begin

Select g.name, u.name
From sys.database_principals u,
sys.database_principals g,
sys.database_role_members m
Where g.principal_id = m.role_principal_id
And u.principal_id = m.member_principal_id
And u.name <> 'dbo'
Order by g.name, u.name

End

-- Run sp_test from a database containing fixed database role members. The select only runs against master and not the current DB.