This time isn't right either, look for a differential amp, you need 2 inputs, one is the wiper of the pot, the other is a 0V reference, which will be a ground coming from the pot directly to the amp and only connected to it.
In any case, this is a very particular design good practice, if your fader kill isn't critical or this is giving you a hardish time to put together just ignore it and keep going, you probably make a few mistakes down the road and learn from then, for the next time you'll remember this and getting how it works will be much easier.