Custom fields display through RT::Client::REST

dear all,

I’m using RT and RT::Client::REST::Ticket successfully to get ticket normal
but for custom fields, its not displaying them,

I have a custom field “Module” that I want to display, I use the following:
while (my $ticket = &$iterator) {

    my $cf_module= $ticket->cf(Module);

print EMAIL_FILE "<TR><TD>",$ticket->id,"</TD><TD>"
    ,$ticket->subject, "</TD><TD>", $ticket->status,"</TD><TD>",

$cf_module does not show anything
trying $cf_module= $ticket->cf(‘Module’);
produce the same result.

I’m using RT 3.4.4 on ubuntu 6.06 server

appreciating your help achieving the objective of displaying ticket details
including custom fields, using the above method or any other.

best regards