Reality checks wont work 100% of the time. I'm taking it you did not become lucid.

Dreams range from completely illogical to decently logical. Sometimes, your hands are normal. Sometimes, the clock works perfectly fine. Sometimes, books look normal. Sometimes, the lights function properly. Sometimes, your reflection in the mirror is perfect.

You can't just do a reality check and expect to become lucid. I've had the same thing happen to me. I did a reality check and didn't become lucid. You need to practice awareness. When you do your reality checks, actually question reality. Question your presence in the world. Observe everything around you. How are you impacting the things around you? What can you smell, taste, feel, hear, or see that doesn't seem like reality? When you do a reality check, whether it be in real life, or in a dream, become aware of yourself and the world around you. I guarantee you will become lucid.