[Audacity] Stereo mix won't record sound.

[Pict]

Attempted to get some sound samples for a small project [Sound effect audio etc] and so far the recording has been completly flat-lined beside recording my Mic, I've allready enabled Stereo mixing but so far still a Flatline to record anything at all.

I got no idea how to fix it at the moment, any Advice would help to record In-game sounds

Heres the video of its issue.