In this paper we present negative results for global scheduling of implicit deadlines periodic systems under EDF. We reconsider the definition of the idle intervals from the uniprocessor case to the multiprocessor case. Unfortunately, this new definition does not provide feasibility results for these systems. We prove that the periodicity of an EDF-feasible schedule does not hold from the uniprocessor case to the multiprocessor case. A discussion for calculating this instant is provided.