protected void showButton_Click(object sender, EventArgs e)
{
reportGridView.DataSource = aDiseaseManager.GetDiseaseWiseReportsBetweenDates(diseaseDropDownList.Text,
DateTime.Parse(firstDateTextBox.Value), DateTime.Parse(lastDateTextBox.Value));
reportGridView.DataBind();
ViewState["data"] = aDiseaseManager.GetDiseaseWiseReportsBetweenDates(diseaseDropDownList.Text,
DateTime.Parse(firstDateTextBox.Value), DateTime.Parse(lastDateTextBox.Value));
}