GTM/DNS external monitor for proxy

I have setup a external monitor on our GTM using https://support.f5.com/csp/article/K31435017

I want to monitor if the proxy has internet access or not. 

if I run the script on F5 cli it return "up" but when i attach it to the I get below error

Monitor instance /Common/SquidMonTest x.x.x.x:xx CHECKING --> DOWN from x.x.x.x (state executable not found)

I enabled debugging but it did not help much.

appreciate it if someone can point me in the right direction