Public Function F_CalculaArbol(s_ruta As String, s_clavepadre As String) As
Boolean
Dim clave As String
Dim d1 As String

d1 = Dir(s_ruta, vbDirectory)
Do While d1 <> ""
    If d1 <> "." And d1 <> ".." Then
        If (GetAttr(s_ruta & d1) And vbDirectory) = vbDirectory Then     'Is
a Folder
            clave = "C" & l_contador
            Set nodX = Form1.arbol.Nodes.Add(s_clavepadre, tvwChild,
clave,d1)
            l_contador = l_contador + 1
            x = F_CalculaArbol(s_ruta & d1 & "\", clave)

        Else        'Is a file
            clave = "A" & l_contador
            Set nodX = Form1.arbol.Nodes.Add(s_clavepadre, tvwChild,
clave,d1)
            l_contador = l_contador + 1

        End If

    End If
    d1 = Dir

Loop

F_CalculaArbol = True

End Function

This function returns next error :
Call to a procedure or arguments no valids

This statement IS NOT recursive, thus, when you return
from the first recursion (a lower level), VB cannot continue
to generate the next file of the upper level.

A way to solve this problem is to insert all first-level
nodes, then, for each node of first level, insert all
the second-level nodes, and so on.