Arrays in param is converted to empty XML

[wa05]

Hi Im sending an array of params like this and WebService receives emtpy the elements that are arrays...

[params] => Array
        (
            [token] => 4b36f529065d34ec28b7ffcb83b0c3f6
            [id] => 0
            [provider_id] => 321
            [number] => A0FC60D7C
            [orders] => Array
                (
                    [0] => 15665
                )
            [bodies] => Array
                (
                    [0] => Array
                        (
                            [id] => 6803
                            [DecVal1] => 16
                        )
                )
        )

This is the xml that Nusoap is going to send.. What could it be?
<InformeRecepcion_Guarda xmlns="http://mapplics.com/"><token>4b36f529065d34ec28b7ffcb83b0c3f6</token><id>0</id><provider_id>321</provider_id><number>A0FC60D7C</number>**<orders></orders><bodies></bodies>**</InformeRecepcion_Guarda>