LTSPICE Simulation error

Dear Team,

Please help me find out what is going wrong in the LT spice Simulation.

I have attached my Simulation file.

My Input is 28VDC and I need a variable output (1.5V to 15V @10A).

A 20K digital potentiometer will be used as feedback resistor(RFB2) in the actual circuit.(RFB2 = 778Ohms for 15V Output and RFB2=16000Ohms for 1.5V Output , with RFB1 as 14000Ohms)

In the simulation I have not used a Potentiometer. Iam trying to get the Output Voltage in the simulation by manually changing the RFB2 resistor.

But after simulation, output voltage is shown as some mV.

Please verify my Simulation file and suggest any correction if required.

Regards

Sreelakshmi A

8233.LTC3810.asc