Call external sub with Workbook_BeforeClose with Excel 2010

[sgremmo]

hi, when i try to close a workbook with this vba

Public Sub Workbook_BeforeClose(cancel As Boolean)
utente = Application.UserName
sgBeforeClose (utente)
End Sub

Public Sub sgBeforeClose(utente)
MsgBox "utente"
End Sub

it works fine only if sub sgBeforeClose is in the same .xlsm.
When I move sgBeforeClose in other .xlsm I obtain sub non definited.

Thank for every help.