LTC3862-1 GATE PIN(1-2) ALWAYS HIGH and MOSFET Gate Pın ON

We are using a LTC3862 for a SMPS (switching mode power supply, 24V to 130V, 0.5A). Firstly, we modelled the design in LTSpice and it worked better than the design installed on the perforated plate.

The MOSFET's gate pin is always on ("high") and the LTC3862 gate pin voltage value is 5V constantly. In LTSpice, the LTC3862 gate pin value is 0V to 10V and it is working. What could be causing this?