can't mount my NAS with volumio 1.55

when i used volumio 1.4 or 1.5 , i have no problem to mount my NAS(2To) wiith the Web UI, But now i try to use a Rpi 2 and hifiberrydigi with 1.55 .All is works, listening music on a USB key or with airplay but i can’t mount the NAS, red cross with error message:
mount error(13): Permission denied Refer to the mount.cifs(8) manual page (e.g. man mount.cifs)
what can i do ?
thank for your help