Hi
This query "select sCode_value from Codes where
gCode_Id = '853C63ED-D7CC-4E86-965E-F425A53E1BA2' " which you have mentioned will work.
As Carl said if no rows are being returned check whether the uniqueidentifier value is being used.
BTW why do you want to use CAST. Is'nt the column datatype uniqueidentifier ?
"Keep Trying"