Hi, I bought a "New DB-036" model from Carrefour for $109 on last Friday. This is the first time Iím using it. It has only one LED on the knob. I just check the digicabi with out putting any of my equipment inside. Then I noticed when the knob is at 12 o'clock position time to time it is giving different readings on the digital RH meter. I wonder my set is a faulty one. how can I resolve this???