I am getting an error when reading data from sqldatareader

Question

 

Hii

 I am attaching the command

 

SqlCommand cmd = new SqlCommand("select SUM(cast(UserIncomeDetail_Amount as int)) as amount from ft_UserIncomeDetail where User_Uniq='Harish'", con);

con.Open();

sda=cmd.ExecuteReader();

if (sda != null)

{

ViewBag.income = sda["amount"];

}

 

 

error-

System.InvalidOperationException: 'Invalid attempt to read when no data is present.'

please the fix issue