OIP-04122: Bind variable not fully enabled

I would like to execute a stored procedure from an ASP page but the folowing  line code would get OIP-04122 error :

[Quoted] OraDatabase.Parameters.Add "DIR", DIR, ORAPARM_OUTPUT, 1

could someone help me ....
thanks

here is the entire procedure :

Public Sub GET_NOM_FIC(ByRef DIR, ByRef NOM, FICHIER, ByRef OraDatabase)

   OraDatabase.Parameters.Add "DIR", DIR, ORAPARM_OUTPUT, 1     OraDatabase.Parameters.Add "NOM", NOM, ORAPARM_OUTPUT, 1     OraDatabase.Parameters.Add "FICHIER", FICHIER, ORAPARM_INPUT, 114   'OraDatabase.ExecuteSQL ("Begin asp.GET_NOM_FIC(:DIR, :NOM, :FICHIER); end;",0)

  DIR = OraDatabase.Parameters("DIR").Value   NOM = OraDatabase.Parameters("NOM").Value

  OraDatabase.Parameters.Remove "DIR"
  OraDatabase.Parameters.Remove "NOM"
  OraDatabase.Parameters.Remove "FICHIER"