It does not give any result because the alias is not found in table 'alias' from database 'postfix' in mysql.
When it finds an alias, it returns its pointing.
May be you drop that alias..??
Try to recreate any other alias, and check if is working.
Check your '/var/log/maillog' file for error messages, with the folloing command:
# egrep --color '(warning|error|fatal|panic):' /var/log/maillog