Invalid specified cast

This error occurs when trying to run Cross-Validation Distance. The illegal cast occurs during the creation/setup of the SummaryPercentages object used to generate the TopN graph. Will need further investigation.

Error in Distance! Specified cast is not valid.
  at Wfccm2.DistanceReport.CreateSummaryPctgs(ArrayList drs) in F:\graywh\My Documents\Visual Studio Projects\C#\wfccm2\DistanceReport.cs:line 677
  at Wfccm2.DistancePanel.DistanceRun(DoubleProgress distProgress, IDataSet, ids, DataGrouping dg, Score scr, CriteriaManager cm, String dir, Int32 kFold, IDataSet tids, DataGrouping tdg) in f:\graywh\my documents\visual studio projects\c#\wfccm2\distancepanel.cs:line 1800