Hi, some time ago I bought a 6022be from amazon and I only tested it with the square signal that it includes and everything seemed to be in order. Today I used it to measure a 12v square signal and the square signal appeared but 5v, I tried with a conventional 9v battery and the signal it showed was 5v, it seems that the maximum voltage it shows is 5v, I would appreciate it if you could help me. Thank you