Last constraint resulting in no solution for solomon instances

Hi Alexandru Furculita,
Thanks for sharing code. I am using this code for one of my assignment. I am using suleman's (https://www.sintef.no/projectweb/top/vrptw/solomon-benchmark/100-customers/) instances for the evaluation purpose but  when I run my code it gives me no solution when I remove last constraint it start giving me solution why this is so? Could you please explain.  