How to get value from sql server

Question

string Bill;
     protected void Page_Load(object sender, EventArgs e)
     {
   Bill = "22-01-2020 ";

         if (!IsPostBack)
         {
             cash();

         }
     }
     protected void cash()
     {
         string query = "select SUM((CASE WHEN ISNUMERIC([Total])=1 THEN CONVERT(MONEY,[Total]) ELSE 0 END))AS [Amount] from Bill where Bdate = CONVERT(DATETIME, '" + Bill + "', 105) and Btype ='Cash'";

         con.Open();
         cmd = new SqlCommand(query, con);
         SqlDataReader dr;
         dr = cmd.ExecuteReader();

         if (dr.Read())
         {
             string amount = dr["Amount"].ToString();
             lblCash.Text = amount.ToString();
             con.Close();
         }
         con.Close();
     }

This query  value is Null,

 

How to i get Sum value from sql  

 

Thanks all