Eror Raw Query Laravel

Saya mau join table menggunakan Raw Query, tidak ada eror tetapi datanya tidak muncul. Foreign Key saya dalam bentuk String Raw Query

$subs = DB::table('programs')
              ->join('subprograms', 'programs.id_prog', '=', 'subprograms.id_subprogram')
              ->select('programs.id_prog', 'programs.nama_prog', 'subprograms.*')
              ->get();

view

    @foreach($subs as $users)
                        <tr>
                          <td>{{$users->nama_prog}}</td>
                          <td>{{$users->level}}</td>
                          <td>{{$users->room}}</td>

database program

  public function up()
    {
        Schema::create('programs', function (Blueprint $table) {
            $table->string('id_prog',11)->primary();
            $table->string('nama_prog',50);
            $table->string('duration',11);
            $table->string('implementation',50);
            $table->string('day',25);
            $table->string('time',25);
            $table->char('cost',11);
            $table->timestamps();
        });
    }

Database sub program

 public function up()
    {
        Schema::create('subprograms', function (Blueprint $table) {
            $table->increments('id_subprogram');
            $table->char('level',11);
            $table->string('room',25);
            $table->string('id_teacher',11);
            $table->string('id_prog',11);
            $table->timestamps();
        });
    }