Caravan doesn't move and even sleep, eat

[Waterkey]

When I sent my caravan, It didn't move even at noon
and they didn't sleep at night. didn't eat any kind of food they have.

This is the link of the save file
https://drive.google.com/file/d/0B1WVpMSC-EeHREtMd3FWcGwtNXM/view?usp=sharing

I'm not sure this log is about the problem, but this is maybe related to it

System.NullReferenceException: Object reference not set to an instance of an object
  at RimWorld.PredatorThreat.get_Expired () [0x00000] in <filename unknown>:0
  at RimWorld.Faction.FactionTick () [0x00000] in <filename unknown>:0
  at RimWorld.FactionManager.FactionManagerTick () [0x00000] in <filename unknown>:0
  at RimWorld.Planet.World.WorldTick () [0x00000] in <filename unknown>:0
  at Verse.TickManager.DoSingleTick () [0x00000] in <filename unknown>:0


the weired thing is that when I started new game for the test with same mods, a caravan in new game worked fine. I don't know what the problem is. I want to keep playing my old save file.
how should I fix this bug?