private void OnButtonCreateClick(object sender, EventArgs e) { int index = this.cbSubjects.SelectedIndex; if (index < 0 || index >= avaialableClasses.Count) { return; } var cls = avaialableClasses[index]; var report = new ClassReport(); SQLConnections.FillResultReportsByClass(this.teacherID, cls.ID, this.start, this.end, report); this.Close(); new ClassReportForm(report).ShowDialog(); }