I'm SO sorry I took so long to get to this. It's been fixed now. My apologies!!
Apparently I'm having problems saving over old brush sets with the same name, so I have to make a new file every time I add a new brush. I hope it works now.
And once again, sorry it took me so long to fix it.
This'll teach me to check it more frequently. Maybe.... (Although, I'm shocked that I was away from here for so long. I must've been busy. I usually lurk if nothing else.)