Why am I getting a domain taken error?

[Doug Sisk]

The lookup command says its available, but when I try to register I get
'domain taken'.

I'm using the php version of the client, and it works with the test
environment, I'm trying to move to production, but I can't figure this
out.

Thanks,
Doug

Command:
Array
(
    [action] => sw_register
    [object] => domain
    [attributes] => Array
        (
            [reg_username] => das
            [reg_password] => xxxxxx
            [custom_nameservers] => 0
            [bulk_order] => 0
            [domain] => sisknet.com
            [period] => 1
            [auto_renew] => 0
            [contact_set] => Array
                (
                    [owner] => Array
                        (
                            [first_name] => Douglas
                            [last_name] => Sisk
                            [org_name] => Individual
                            [address1] => 15 Wharton Way
                            [address2] => 
                            [address3] => 
                            [city] => High Bridge
                            [state] => NJ
                            [postal_code] => 08829
                            [country] => US
                            [phone] => 908 638-3305
                            [fax] => 
                            [email] => [EMAIL PROTECTED]
                        )

                    [admin] => Array
                        (
                            [first_name] => Douglas
                            [last_name] => Sisk
                            [org_name] => Internet Business Services
                            [address1] => 15 Wharton Way
                            [address2] => 
                            [address3] => 
                            [city] => High Bridge
                            [state] => NJ
                            [postal_code] => 08829
                            [country] => US
                            [phone] => 908 638-3305
                            [fax] => 908 638-3570
                            [email] => [EMAIL PROTECTED]
                        )

                    [tech] => Array
                        (
                            [first_name] => Douglas
                            [last_name] => Sisk
                            [org_name] => Internet Business Services
                            [address1] => 15 Wharton Way
                            [address2] => 
                            [address3] => 
                            [city] => High Bridge
                            [state] => NJ
                            [postal_code] => 08829
                            [country] => US
                            [phone] => 908 638-3305
                            [fax] => 908 638-3570
                            [email] => [EMAIL PROTECTED]
                        )

                    [billing] => Array
                        (
                            [first_name] => Douglas
                            [last_name] => Sisk
                            [org_name] => Internet Business Services
                            [address1] => 15 Wharton Way
                            [address2] => 
                            [address3] => 
                            [city] => High Bridge
                            [state] => NJ
                            [postal_code] => 08829
                            [country] => US
                            [phone] => 908 638-3305
                            [fax] => 908 638-3570
                            [email] => [EMAIL PROTECTED]
                        )

                )

        )

)
Result:
Array
(
    [is_success] => 0
    [protocol] => XCP
    [_OPS_msg_type] => standard
    [object] => SW_REGISTER
    [_OPS_msg_id] => 180.257378557502
    [response_text] => Domain taken
    [response_code] => 485
    [action] => REPLY
    [_OPS_version] => 0.9
)