In my opinion, this answer should go. It has no explanation, and while it may help someone, in light of the other answers and the number of downvotes, it doesn't really belong.
I can't enable snapshot isolation
ALTER DATABASE mydb
SET READ_COMMITTED_SNAPSHOT ON;
ALTER DATABASE mydb
SET ALLOW_SNAPSHOT_ISOLATION ON;
query still 0 rows working 5 days and nothing happens without error message.
MSSQL 2008 server Database is 22GB