How can I call a Simulink function that is located 2 levels above the Function Caller block?

I have a function caller block two levels beneath a Simulink function. If I call the function with just one level apart, the model will simulate flawlessly. With two levels apart, Simulink will return the Error: [Provide Input argument specifications and Output argument specifications for the Function Caller block '...' because the corresponding Simulink function could not be resolved to within this hierarchy, model, or any referenced model.]

I can't place function and function caller somewhere else.