Reading data from SQL - C# and ASP.NET

I'm trying to read data from MS-SQL and assign returned the value in the ASP.net page which is text field.

It keeps showing like
"Invalid attempt to read when no data is present.."
Exception Details: System.InvalidOperationException: Invalid attempt to read when no data is present.

when I query those statement in MS-SQL, data is surely there..

I'm trying to figure it out. I could not resolve yet..
Can I assign like

EmployeeFirstName.Text = sdr["fname"] == DBNull.Value ? String.Empty : ((string)sdr["fname"]).Trim();

Thanks in advance.

my current code in c# FYI
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using (var cmd = conn.CreateCommand())
      {
         conn.Open();
         cmd.CommandText = "SELECT * FROM [Employee] with (nolock) where eID=@eID";
                    cmd.Parameters.Add(new SqlParameter("eID", SqlDbType.Int, 0) { Value = eIDOf.SelectedItem.Value });
                    cmd.Prepare();
                    using (SqlDataReader sdr = cmd.ExecuteReader())
                    {
                        EmployeeFirstName.Text = sdr["fName"] == DBNull.Value ? String.Empty : ((string)sdr["fName"]).Trim();
                        sdr.Close();
                    }

    }






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