Highlighting dates in Calendar from dates in Database

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C#

ASP.NET

Hi! I'm doing a program that will highlight the dates in a calendar where the dates are from the database. I'm using the following code:

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using MySql.Data.MySqlClient;
using System.Drawing;
using System.Net;
namespace WebApplication1
{
    public partial class cal : System.Web.UI.Page
    {
        protected DataSet dsHolidays;
        //MySqlConnection objConn;
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                Calendar1.VisibleDate = DateTime.Today;
                FillHolidayDataset();
            }
        }

        protected void FillHolidayDataset()
        {
            DateTime firstDate = new DateTime(Calendar1.VisibleDate.Year,
                Calendar1.VisibleDate.Month, 1);
            DateTime lastDate = GetFirstDayOfNextMonth();
            dsHolidays = GetCurrentMonthData(firstDate, lastDate);
        }

        protected DateTime GetFirstDayOfNextMonth()
        {
            int monthNumber, yearNumber;
            if (Calendar1.VisibleDate.Month == 12)
            {
                monthNumber = 1;
                yearNumber = Calendar1.VisibleDate.Year + 1;
            }
            else
            {
                monthNumber = Calendar1.VisibleDate.Month + 1;
                yearNumber = Calendar1.VisibleDate.Year;
            }
            DateTime lastDate = new DateTime(yearNumber, monthNumber, 1);
            return lastDate;
        }

        protected DataSet GetCurrentMonthData(DateTime firstDate,
             DateTime lastDate)
{
    DataSet dsMonth = new DataSet();
    string connectionString = "SERVER=localhost;DATABASE=firstschema;UID=root;PASSWORD=1234;";
        
    MySqlConnection dbConnection = new MySqlConnection(connectionString);
    String query;
    query = "SELECT Task_Date FROM nametable WHERE Task_Date >= @firstDate AND Task_Date < @lastDate";
    MySqlCommand dbCommand = new MySqlCommand(query, dbConnection);
    dbCommand.Parameters.Add(new MySqlParameter("@firstDate", firstDate));
    dbCommand.Parameters.Add(new MySqlParameter("@lastDate", lastDate));

    MySqlDataAdapter sqlDataAdapter = new MySqlDataAdapter(dbCommand);
    try
    {
        sqlDataAdapter.Fill(dsMonth);
    }
    catch {}
    return dsMonth;
}

        protected void Calendar1_DayRender(object sender, DayRenderEventArgs e)
        {
            DateTime nextDate;
            if (dsHolidays != null)
            {
                foreach (DataRow dr in dsHolidays.Tables[0].Rows)
                {
                    nextDate = (DateTime)dr["Task_Date"];
                    if (nextDate == e.Day.Date)
                    {
                        e.Cell.BackColor = System.Drawing.Color.Pink;
                    }
                }
            }
        }
        protected void Calendar1_VisibleMonthChanged(object sender,MonthChangedEventArgs e)
        {
            FillHolidayDataset();
        }
    }
}

My problem is, it only highlight the dates present in the current month. When I move the calendar into the next month, no highlights is shown. Also, when I return to the previous month, the highlighted dates before are gone.

How can I fixed this? Thank you in advance.