Mail alias import through Remote API - problem

Hello,
I'm trying to import email users using remote API but it doesn't work.
Here's part of code that I use to import aliases

Code:

$alias_params = array(
                        'server_id' => '1',
                        'source' => $al[0],
                        'destination' => rtrim($al[1]),
                        'type' => 'alias',
                        'active' => 'y',
                        'sys_userid' => $al[2],
                        'sys_groupid' => $al[3]
                );

                try {
                    echo "source: $al[0] <br> destination: $al[1] $al[2] $al[3]<br>";
                    $alias_id = $client->mail_alias_add($session_id,9,$alias_params);
                    echo "Alias $mb[0] for $mb[1] created<br>";
                } catch (SoapFault $e){
                    die ('Alias creation error: '.$e->getMessage());

It's the only part of script that's not working.
When I run script it gives me following error:

Adding aliases through web UI works fine, but I have several hundreds of accounts to import and it would help if I could automate it in some way.
Does someone have any workaround this problem?
ISPConfig version 3.1.15p3

Thank you for any help.
Piotr

 

You were right.
Probably it got copied from test server and wasn't spotted
Thank you for fast help

Regards
Piotr Perkowski