PROBLEM WITH LISTBOX METHOD RETURN LISTBOX

Dear all, I have a problem and I don’t know how to solve.

I have a containercontrol with one LISTBOX.

I have a method that returns a listbox on a button.

Then I do

LB_Escalados = Crea_List(LB_Escalados,TF_KDesde.text, TF_KHasta.text) where LB_Escalados is a listbox

This methos returns a listbox, that overwrites the older.

Function Crea_List(LB_Escalados as listbox,Desde as String, Hasta as String) as listbox

But I have an error that says that method doesn’t exist.

If I do the same on WEB PROJECT it works without problem.

Any suggestion?