PHP Code:
register_think("check_speed", "Set_Terrorist_Visibility")
set_pev(TaskEnt, pev_classname, "speedometer_think")
Code:
/* Registers a think action to a function by classname. */
native register_think(const Classname[], const function[]);
1. The entity's classname that thinks must the same in the two natives.
2.
Set_Terrorist_Visibility isn't called anywhere in your code.