I have a level 8 sorcerer. I have the Unstable Familiar spell associated with a button on my Skills bar. When I have sufficient Magic available, and I press the skills button associated with the Unstable Familiar, the familiar appears, but no matter how long I hold the skills bar button, the familiar disappears as soon as I let the button go. A handful of times, the familiar does resolve and stay around, and in those cases, it works as I would expect, following me around and attacking enemies that I attack.

What am I doing wrong? I see other characters in the game with these familiars following them around all over the place.