If the macro is in a standard module, you should have access to it.
As long as the module is not spec'd as Option Private Module.
We are talking about a Sub, not a Function, correct?
My 'checklist' for access to a Sub/Function is:
Make sure you are spelling the name correctly.
Is Intellisense 'popping up' and prompting for arguments?
You won't need to use parentheses when calling a Sub. At best, they get in the way, causing a compile-time error. At worst, parentheses may be interpreted as type-forcing, causing a run-time error. If your Sub all of a sudden returns "Object Required" run-time errors, look for 'extra' parentheses.
With a function, you need to have the arguments enclosed in parentheses IF you are wanting to assign the result of the function. You could call a function without enclosing arguments within parentheses; just don't assign the result to anything.