private void CalculateTransaction(object sender, RoutedEventArgs e) { if (this.dataChanged && IsValidForCalculations()) { double eventFee = this.transaction.GetStrictEventFee(this.cmb_EventName.Text); transaction.isLate = false; transaction.lateTime = 0.0; CheckForLateTime(DateTime.Parse(this.txt_CheckOut.Text).ToString("HH:mm:ss"), DateTime.Parse(this.txt_Date.Text).ToString("yyyy-MM-dd")); this.txt_TransactionTotal.Text = String.Format("{0:0.00}", transaction.CalculateTransaction(this.txt_CheckIn.Text, this.txt_CheckOut.Text, this.cmb_EventName.Text, eventFee)); } }