Im not good with that but just trying to help
1- Ask someone to do the skill infront of you to make sure its the one u saw.
2- Check if your character is a venomancer.
3- Check if u have the skill or not.
4- Press U > UI > Do the effects bar to the far right.
5- Not working ? Press U > System > move the Overall bar for 1/2 steps. then try the skill
6- Not working ? Right click on the desktop and check ur graphic card options then Check 3D settings and add perfect world to it.. then try to enable all the sh1t for it
7- Not working ? Kick ur CPU with ur foot and try to break it abit.
8- Not working ? Bring a hammer then smash CPU with it, carry the CPU after and throw it from window, if anyone tries to stop you Just Kill him/her.
9- Bring a knife and go towards ur dad and ask him politly to buy u a new one as ur hiding the knife behind if he refuse, try to do a kitty face.. still refusing ? get the knife and move it closely over his neck and make him buy a new one.