I finally played with the security in Mgt Studio.
We are encrypting the SYMMETRIC KEY with a CERTIFICATE.
So...how I made it work was by creating a database role to which I gave CONTROL rights to the CERTIFICATE and VIEW DEFINITIONS rights to the key.
Now any member of the role has the ability to open the symmetric key encrypt/decrypt and then close the symmetric key.
And by the way thanks for the reference. That was my first reading for SQL 2005 encryption. Very good, clear and concise.