Unable to use the Soul Cube

[Phoenix Nebula]

Recently, I beat the guardian and had finally acquired the Soul Cube. I was hoping to use it again stronger demons but was unable to. Each time I equipped it, I tried using it by firing it like any other weapon in the game. Instead of being able to use it however, it would switch me back to the weapon that I was using beforehand. I don't know if it's because there's a separate button I need to use, but I'm really lost at the moment and could use some help.

P.S. I did install a mod before playing (Realistic Weapons) so that might be what's causing it, but I'm not too sure if I'm being honest.

[smallen7]

You need to kill a number of demons to power up the cube.

[Phoenix Nebula]

Originally posted by smallen7:

You need to kill a number of demons to power up the cube.

Yes, that I am aware of. The problem was that it still wouldn't work even then. I started a new save file where the soul cube wasn't powered up yet and even after killing more than fifteen demons, it still wouldn't activate at all.

[Tiny Trees]

Check which button operates the souls cube. I can't remember if there is a separate button.

You know when the soul cube is charged because it speaks to you, and says, "Choose us".