sql problems with disntinct

I have a table in my database with:

• horarioId
• horarioParagemId
• horarioLinhaId
• horarioHora

I make INNER JOIN of the table rows:

• linhaId
• linhaNome

I do INNER JOIN of the table stops:

• paragemId
• paragemRua
• paragemLatitude

• paragemLongitude

  Example of the schedules table

ScheduleId: 1 scheduleParagemId: 3 scheduleLinhaId: 4 scheduleTime: 22: 00: 00

ScheduleId: 2 scheduleParagemId: 3 scheduleLinhaId: 4 scheduleTime: 21: 00: 00

The goal is only to receive the coordinates where the id of the stops are different. The code I've done works with paragemLatitude or paragemLongitude , but does not work with paragemId

include_once('seguranca.php');
protegePagina();

$sql="SELECT DISTINCT horarioParagemId
      FROM horarios
      INNER JOIN paragens ON paragemId = horarioParagemId
      INNER JOIN linhas ON horarioLinhaId = linhaId
      WHERE horariolinhaId = " . $_GET['filtrapronto'];

$_SESSION['latitudefiltra']= array();
$_SESSION['longitudefiltra']= array();
$result=mysqli_query($con,$sql);

while($dados=mysqli_fetch_array($result)) {

    $_SESSION['latitudefiltra'] [] = $dados['paragemLatitude'];
    $_SESSION['longitudefiltra'] []  = $dados['paragemLongitude'];
}

$obj = new stdClass();
$obj->Latitudes=$_SESSION['latitudefiltra'];
$obj->Longitudes=$_SESSION['longitudefiltra'] ; 
echo json_encode($obj);