I'm guessing here but I think you're using an ODBC connection? And have a class instance called $conn which is dealing with this?
What does $conn-Open(...) give you back?
Also what does $users equal? Is it a recordset? An array?
As for the query I believe MSAccess (JetSQL) will be ok with the fact you have used [ square brackets ] for encapsulating the table name with spaces, although I think you can also use " inverted commas " as well. (Take care to escape them in your "" string

)
As for the Open string, it really does depend on how the Open function deals with the string, or how the ODBC connector splits the string up. It might not like spaces, but it seems to be ; separated so it should be fine.
All in all, any errors? This'll give us a good hint to start.