Zero with a line through it

Hello,

I hope I'm in the right topic, my problem, which I find very frustrating and simple, is that I bought a Creative headset with a microphone, I installed it and I'm being asked for an activation key. Unfortunately, there's a weird symbol in it, it's either an O or a 0 with a diagonal line inside but it doesn't extend beyond the 0.
Ø = that's not it because the line extends...

Thanks in advance!