Instruct: Classify the given Amazon review into its appropriate rating category
Query: Won't lock closed

I ordered this last year. Works great, but has never locked closed. Thought it was just supposed to be held shut, so that's what I've always done. Realized it should be able to lock. I've adjusted the pressure dial and have tried pushing extremely hard even when closing it, but it never has locked. Hoping to find answers, I took to the manual and the internet without any luck.