No wireless connection on PI3

Hello , I just downloaded the version volumio-0.928-2016-06-30-pi and installed on my raspberry3 with hifiberry DAC plus. Everything works fine except the wireless connection . If I leave connected the ethernet cable and enter the network menu , it says there are some wireless networks but not mine that is 30 cm far. Can you help me? Thanks

Is your wireless network N or AC?
Which channel is it on?

My network is N and my router is on auto channel. Yesterday I had to reduce signal power on router to 60% and so Raspberry could see my network and worked. This morning, it’s not working, I don’t know why!

I forgot to tell I put a line in config.txt because I have a DAC:
“dtoverlay=hifiberry-dacplus”. But I think it’s not related to my problem.
Anyway, now I re-wrote SD card and all is workin’! The only strange thing is that if I disconnect wired lan, network menu says I’m still connected (see attachment)