We reexamine the massive graviton dark matter scenario (MGCDM) which was
recently considered as an alternative to dark energy models. When introducing
the native and effective equations of state (EoS), it is shown that there is no
phantom phase in the evolution toward the far past. Also we show that the past
accelerating phase arises from the interaction between massive graviton and
cold dark matter.Comment: 13 pages, 6 figure