Math functions not working on network system

Math functions not working on network system

I have a system with a network. The master PC communicates to the PLC but the User runs the Zenon on the local PC. Math functions only work if the variables are I O.
For example I have a math function with a bool output X01 > 13
This works if X01 is a PLC I O variable but not if it is an internal variable, it always gives false even if the variable is greater than 13. Is this because the application is networked?
And how can I get the math function to work correctly on an internal variable?

This is a migrated post! Originally posted on 12.12.2014 by user mjackson. Please be aware that information can be outdated.