Sfglenrock

Hi. Newbie here. I have a G-17 that I've had hooked up to my network in the past. Now I'd like to just use the 3.5mm input jack. I've tried pushing the I/O button to get the three flashes but still get no sound. I haven't used this for a few years, so has something changed and caused an issue or am I just missing something simple? Any help would be welcome. Thanks.