retrieve allowed channels via API

Hi to all,
I want to retrieve allowed-channels on interface via API.

In terminal the corrrect command is “interface wireless info allowed-channels wlan1”

I try to implement that via api but I receive nothing:

<<< /interface/wireless/info/allowed-channels
<<< =interface=wlan1
<<<

!re

!done

someone know how to fix it?
Thanks in advanced
regards
Roberto