i have grid which creates in code. it adds dynamc columns. when a call such code 

CalcSettings calcSettings = null;

        calcSettings = this.UltraWebCalcManager1.GetCalcSettings(this.ulsum);

        //Set an alias to save some typing and make the formulas a little easier to read.
        calcSettings.Alias = "sum";

        //Set the PropertyName so the CalcManager know what property of the control to use
        calcSettings.PropertyName = "Text";

        //Set the formula
        calcSettings.Formula = "sum( [//TaskObjGrid/Tasks/pak_obj_source_id] )";

it don't calculate like it ca'n find columns . can you help me?