Problème résolu, pour ceux qui veule le code voila :
@SideOnly(Side.CLIENT)
@Override
public boolean onBlockActivated(World p_149727_1_, int p_149727_2_,
int p_149727_3_, int p_149727_4_, EntityPlayer p_149727_5_,
int p_149727_6_, float p_149727_7_, float p_149727_8_,
float p_149727_9_) {
if(p_149727_1_.isRemote)
{
Minecraft.getMinecraft().displayGuiScreen(new GuiTeleporteur());
}
return super.onBlockActivated(p_149727_1_, p_149727_2_, p_149727_3_,
p_149727_4_, p_149727_5_, p_149727_6_, p_149727_7_, p_149727_8_,
p_149727_9_);
}