The Standby (Reset) pin is not locked down. The panel 12V backup battery is low or missing. Using the wrong product handler, for example, using 2112 instead of 2212. Too much Current Draw on panel. Disconnect devices from Aux Power and try again. Noise or interference on the keypad Data Bus. Disconnect all wires on the panel data terminals. Not enough free memory in the D5200 Programmer. There should be 60K free memory. Refer to KB article: How to Operate the D5200 Hand Held Programmer. The 2212 handler may be corrupted in the D5200. Delete the 2212 handler and re-download it. Refer to KB article: How to Operate the D5200 Hand Held Programmer. Low batteries in the D5200. Replace batteries using 4 C cells. Trying to program a panel that is not powered up The programming cord is not securely connected to the panel programming port or may be damaged. The DX4010V2 comes with a cord with a 4-pin Molex connector on one end and phone connector on other end. This cable may work as a substitute.