Building a wifi remote control

[From Hell]

ok, i just found on the MPC man page a little more commands

https://www.mankier.com/1/mpc#Examples_(TL;DR)

But when i want to try with 'prev"
http://moode/command/?cmd=prev

i'v got this message:
readMpdResp(): Error: response $str[0]=(ACK [5@0] {} unknown command "prev")

Any idea ?

PS: how to insert link in this board ?