Why doesn't Infinite Tsukuyomi work on Tobirama Senju? Manga Spoiler Alert
In the latest manga chapter (677), Madara successfully initiated the Infinite Tsukuyomi.
However, Tobirama Senju seems to be unaffected by this. Why is that?
See reference image below:
Given the fact that none of the Edo Tensei'd Hokages were affected, I'm guessing that Edo Tensei reanimated people are not affected by it. 

There wasn't much said about it anyway, but that's the option that makes most sense.