Mach refusing to detect an E-stop input

[RobC]

E-stop was working prior to a re-build and install and now is deciding not to work as required. Mach 3 is not detecting any inputs on pin 10 or pin 13 respective to how I have said pin input allocated.

I've got 5.5v between pin 4 and pin 10, then once I break the circuit via the e-stop It drops to 0v which shows it works fine.

This is the pin allocation within mach, I've got one side of the e-stop wired into ground and the other into pin 10 and set to active low.

Can anyone tell me am I looking at an issue within mach or a hardware issue.