Track - set output routing channel not working

Hello,

I am using a reaction to assign a specific routing destination to the selected track when I press a specific pad.

The command is :

self.song().view.selected_track.output_routing_channel = self.target_by_name(self.song().view.selected_track.available_output_routing_channels, "bus")

But I get error message in the log :

(NASCA launchpad mini) There's a problem with 'Action Block 1' in reaction 'selected track > route to bus' (from 'Pad 137 was pressed' listener) >>
>> Python argument types in

I think I am missing something related to Python coding ?

Thank you for your help.