VICTIM THOUGHT THE ROOF BOLTER OPR. WAS DONE MOVING THE MACHINE SO HE WENT ALONG THE SIDE OF THE MACHINE WHEN THE OPR. MOVED AGAIN AND CAUGHT HIS FOOT BETWEEN THE RIB AND THE REAR OF THE MACHI NE. CAUSE OF INJURY WAS LACK OF COMMUNICATION. RULES/REGS WAS A FACTOR, SAFETY EQUIPMENT NOT A FACTOR, MINING/EQUIPMENT WAS A FACTOR, MINER PROFICIENCY A FACTOR.