I am stuck and I can¬ít get passed the red barrier. After I kill the yellow walnut head I get into the area were the sniper is and I can kill the sniper and I kill the walnut head that is an orange color. And when I move top the left I hear another one walnut head but I can¬ít see it. So I go and kill the other the purple and the other yellow. I can¬ít find the red walnut head and the blue walnut head, but I can hear one. What can I do I can¬ít go any farther when I get into this area?