A lock that keeps failing is read as feeling unable to protect your private space or set a boundary. Dream books link it to someone or something that keeps getting in despite your efforts.
Has this come up in your dreams before? What was going on in your life then?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.