A tribunal decided this afternoon that referee Dean Whitestone was correct to send off Hayden Mullins in Portsmouth's 3-0 defeat to Coventry City on Tuesday.
The South Coast club had appealed the decision but it was rejected by the tribunal and means that Mullins misses Pompey's trip to Cardiff on Saturday.
Portsmouth boss Steve Cotterill told Portsmouth's official club website: “I’m obviously disappointed. The lads here had put together a really good case. "I didn't think it was even a penalty.“