Microsoft OLE DB Provider for ODBC Drivers error '80004005'

[Microsoft][ODBC Microsoft Access Driver] The Microsoft Jet database engine cannot open the file '(unknown)'. It is already opened exclusively by another user, or you need permission to view its data.

/connessione.asp, line 3
il file di connessione:
codice:
<% dim conn
set conn=server.CreateObject("ADODB.CONNECTION")
conn.Open "driver={Microsoft Access Driver (*.mdb)};dbq="& server.MapPath("/mdb-database/miodb.mdb") 
%>
Da cosa può dipendere questo errore?