I have written an application that allows my users to apply an unbound column to the grid.   Then using formula builder dialogue apply a formula to perform thier own calculations in the grid on existing data.  When they try to add a summary it will only allow count, max and min.  I am assuming this is because when adding the unbound column for the formula I am letting the grid decide the data type to use (found this trick in another post that described a unhandled exception scenario in the calc engine).  If I assign the data type (System.Double) everything works fine.  Summaries work everything seems great until you try to apply a formula in that column that manipulates string data and returns a string.  There is an unhandled exception somewhere in the calc engine that kills the application as per the first article I found that told me about the trick how to not get the unhandled exception.  Typical setup of the code is as follows: 

calcMan.SuspendCalc();

CreateColumnReturn newColumn = CreateFormulaColumn();

if (newColumn.Created)

    {

     gridQueryData.CalcManager = calcMan;

     ShowFormulaBuilderDialog(newColumn.NewColumn);

     }

    calcMan.ResumeCalc();