SqlException not working in C#

Question

I am trying to use the sqlException handler, but it is not working. Tried researching and reviewing everything I know. Using Visual Studio 2017 (latest update), Xamarin, .net 4.7, Windows 10 creators updates. I am using the correct package, but it is not recognized. My code is below. I either must be missing something, or am not seeing something, but this should work as intended. The standard Exception works, but the SqlException is not recognized. Please help.

using System;
using System.Data.SqlClient;
using System.Data.SqlClient.SqlException;

namespace MobileWebServices.SqlClientFiles
{
    public partial class SqlClient
    {
        private int GetMaxECMDataID(string tClientNumber, string tClientPassCode, string tFileID)
        {
            int maxECMDataID = 0;
            var tempConnection = GetTempConnection();
            try
            {
                tempConnection.Open();
                string SQLString = "SELECT max(ECMDataID) as mECMDataID FROM ECMData WHERE FileId = " + "'" + tFileID + "'" + " and iPadLocation = " +
                  "'" + tClientNumber + "'" + " and licensePassCode = " + "'" + tClientPassCode + "'";
                var sqlcommand = new SqlCommand(SQLString, tempConnection);
                maxECMDataID = (int)sqlcommand.ExecuteScalar();
            }
            catch (SqlException sqlex)
            {
            }
            catch (Exception ex)
            {

                Console.WriteLine(ex.Message);
            }

Answer 1

Works as expected on my machine. If you copy the line from the Exception block into the SqlException catch block, you should see output. In my case, I get

The ConnectionString property has not been initialized.