Octavia Estate tailgate

The tailgate can be unlocked as normal pressing the centre(tailgate) button on the key fob. On closing however it sounds as if it is unlocking itself again ( a double sounding click) and the tailgate remains unlocked. The tailgate, and the entire car, can be locked pressing the normal(top) button on the key fob. Is this likely to be a wiring fault or a solenoid problem?

Car is a 2007 Octavia Estate 4x4 FSI.