the truncateonly option only deallocates space up to the last used extent, so you were probably not getting much space back as you had an allocated extent near the end of the database.

the notruncate followed by truncateonly option will work but you can just go for not specifying these options and acheive the same result in one hit. As data will be moved to the front of the file it can be time consuming and intrusive, it will also cause fragmentation in the database, so don't run it after rebuilding indexes!