// Called in Date Diff, when 'ToDatePicker' is selected' void ToValueChanged(object sender, DateTimeValueChangedEventArgs e) { // do a sanity check to make sure dates are valid here DateTime dtFromDate; DateTime dtToDate; string strDisplayResults = ""; dtFromDate = (DateTime)FromDatePicker.Value; dtToDate = (DateTime)ToDatePicker.Value; FormatResultsClass frc = new FormatResultsClass(); frc.FormatDateDiffResults(dtFromDate, dtToDate, out strDisplayResults);// 3 == DATEDIFF textBlock2.Text = strDisplayResults; }