If Proteus was open, close it and open it again.
The TLP250 output should follow the input PWM but with a slight propagation delay (~250ns typical). The output voltage swings from near 0V to about 11.5V (depending on load). tlp250 proteus library download
Connect Pin 6/7 to the gate of an IRF540 N-channel MOSFET through a 10-ohm gate resistor. If Proteus was open, close it and open it again