The Collaborative International Dictionary of English v.0.48:

miscalculation \mis*cal`cu*la"tion\ n.
   1. a mistake in calculating.

   Syn: misreckoning, misestimation.
        [WordNet 1.5]

   2. An error in judgment, especially about the effects of
      action or the likely course of events; as, IBM's
      miscalculation about the impact of microcomputers cost
      them many billions in lost opportunities; Sadam's invasion
      of Kuwait was only his worst, but not his last,
      miscalculation.
      [PJC]

WordNet (r) 3.0 (2006):

miscalculation
    n 1: a mistake in calculating [syn: miscalculation,
         misreckoning, misestimation]