You cannot call a function declared in the global section of a formula from another section, unless the function is marked as const. This rule prevents modification of variables in the global section once the global section has finished executing.
global: func test() endfunc init: test() ; Error!
To fix this, mark the function as const. This means that it cannot modify any global variables, though.
global: func test() const endfunc init: test() ; OK
See Also
Errors