having trouble with a return to main menu script

This is my first game and im using unity and have made 4 game levels(scenes) and a menu scene 0-4 in build order. I can advance levels but after the 4th level i want to return to the main menu but i just cant seem to make it work. It either returns after 1 or 2 levels or fails when it cant load level 5.
I would appreciate any advice you folks can give.

Try commenting out this line:

Level_cap = cur_Level +1;

If you’re on Level 4 it sets the Level_cap to 5.