Display data from DB to ajaxToolkit LINE CHART (Ajax control Toolkit v20.1) Using ASP.NET Webform C# (Dissertation Question)

Question

So, I have some data in my database and I want to display them in a Line chart. I am getting 2 errors when using 2 different approaches. Please refer below.

Am stuck, please help.

In my database I have data such as

month A	total_collected_amount B	Admincut
November	78.6000	2541.4000
October	24.0000	776.0000
September	2522.4000	81557.6000

And the SQL is

SELECT 
    DATENAME(MONTH, pay_date) AS month,
    SUM(pay_admin_fee_mur) AS total_collected_amount,
    SUM(pay_amount_mur) AS Admincut
FROM 
    tbl_payment

WHERE
    tbl_payment.cha_id IS NOT NULL
    AND
    FORMAT(pay_date,'yyyy') = '2023'
GROUP BY 
    DATENAME(MONTH, pay_date), YEAR(pay_date)
ORDER BY 
    month;

My ASPX page is

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="ajaxToolkit" %>
<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder2" runat="server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="head" runat="server">

    <ajaxToolkit:LineChart ID="LineChart1" runat="server" BackColor="64, 0, 0"   
        BackGradientStyle="LeftRight" Height="550px" Palette="None"   
        PaletteCustomColors="192, 0, 0" Width="550px" ChartType="Basic" BaseLineColor="black">
        <Series>
            <ajaxToolkit:LineChartSeries LineColor="Darkblue" Name="Amount collected" Data=""/>           
             <ajaxToolkit:LineChartSeries LineColor="Maroon" Name="Admin cut" Data=""/>            
        </Series>           
    </ajaxToolkit:LineChart>
</asp:Content>

The Code-behind: Try 1 with error.

    public partial class charityeventanalysis : System.Web.UI.Page
    {
        private string _conString = WebConfigurationManager.ConnectionStrings["FARMSdb"].ConnectionString;
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                // Fetch data from the database
                using (SqlConnection connection = new SqlConnection(_conString))
                {
                    string query = "SELECT DATENAME(MONTH, pay_date) AS month, SUM(pay_admin_fee_mur) AS total_collected_amount, SUM(pay_amount_mur) AS Admincut FROM tbl_payment WHERE tbl_payment.cha_id IS NOT NULL AND FORMAT(pay_date,'yyyy') = '2023' GROUP BY DATENAME(MONTH, pay_date), YEAR(pay_date) ORDER BY month;";

                    using (SqlCommand command = new SqlCommand(query, connection))
                    {
                        connection.Open();

                        using (SqlDataReader reader = command.ExecuteReader())
                        {
                            while (reader.Read())
                            {
                                string month = reader["month"].ToString();
                                decimal totalCollectedAmount = Convert.ToDecimal(reader["total_collected_amount"]);
                                decimal adminCut = Convert.ToDecimal(reader["Admincut"]);

                                // Add data to the LineChart series ******* ERROR HERE *******
                                LineChart1.Series[0].Points.AddXY(month, totalCollectedAmount);
                                LineChart1.Series[1].Points.AddXY(month, adminCut);
                            }
                        }
                    }
                }
                LineChart1.ChartTitle = "Yearly collection amount MUR (Rs)";
            }
        }

    }

Error underline for both at Points: saying "LineChartSeries does not contain a definition for Points and no accessible extension method Points accepting a first argument of type LineChartSeries could be found (are you missing a using directive or an assemble reference?)"

The Code-behind: Try 2 with error.

if (!IsPostBack)
            {
                // Fetch data from the database
                using (SqlConnection connection = new SqlConnection(_conString))
                {
                    string query = "SELECT DATENAME(MONTH, pay_date) AS month, SUM(pay_admin_fee_mur) AS total_collected_amount, SUM(pay_amount_mur) AS Admincut FROM tbl_payment WHERE tbl_payment.cha_id IS NOT NULL AND FORMAT(pay_date,'yyyy') = '2023' GROUP BY DATENAME(MONTH, pay_date), YEAR(pay_date) ORDER BY month;";

                    using (SqlCommand command = new SqlCommand(query, connection))
                    {
                        connection.Open();

                        using (SqlDataReader reader = command.ExecuteReader())
                        {
                            while (reader.Read())
                            {
                                string month = reader["month"].ToString();
                                decimal totalCollectedAmount = Convert.ToDecimal(reader["total_collected_amount"]);
                                decimal adminCut = Convert.ToDecimal(reader["Admincut"]);

                                // Add data to the LineChart series ******* ERROR HERE *******
                                LineChart1.Series[0].Data += totalCollectedAmount + ",";
                                LineChart1.Series[1].Data += adminCut + ",";
                            }
                        }
                    }
                }

                // Remove the trailing comma from the Data property ******* ERROR HERE *******
                LineChart1.Series[0].Data = LineChart1.Series[0].Data.TrimEnd(',');
                LineChart1.Series[1].Data = LineChart1.Series[1].Data.TrimEnd(',');

                LineChart1.ChartTitle = "Yearly collection amount MUR (Rs)";
            }

---

Error saying: Error "cannot implicitly convert string to decimal for LineChart1.Series[0].Data += totalCollectedAmount + ","; LineChart1.Series1.Data += adminCut + ",";"

AND error:

"decimal[] does not contain a definition for TrimEnd and no accessible extension method TrimEnd accepting a first argument of type decimal[] could be found(are you missing a using directive or an assemble reference?)"