Confused why MUX implementation is not working:

Posted by davidtaylor23 on Apr 06, 2021; 10:09pm
URL: http://nand2tetris-questions-and-answers-forum.52.s1.nabble.com/Confused-why-MUX-implementation-is-not-working-tp4035921.html

I am not sure if its that the logic is wrong or that I am making some syntax errors, but the file does not seem to load onto the hardware simulator and I am unsure what is wrong.
Here is the implementation:
And(a=a, b=b, out=AandB);
And(sel=sel, b=b, out=BandSel);
Not(in=b, out=NotB);
Not(in=sel, out=NotSel);
And(a=NotSel, b=NotB, out=NotSelNotB);
And(a=a, b=NotSelNotB, out=out1);
Or(a=BandSel, b=AandB, out=out2);
Or(a=out2, b=out1, out=out);

Any help would be greatly appreciated