Problems retrieving access token from Paypal android sdk - php

Question

I am trying to gain a token via the android paypal sdk. I created this cURL inside a php script, but I am unable to update my tkn column in my 000webhost database. The script is called from my app, but I think there might be something wrong with the script. Please let me know if you see anything wrong. Also, it might be that 000webhost does not allow cURL scripts. Please advise. On last minute, one thing that I noticed is that the variable "idclient" and "sekret" are not set as strings. Perhaps this is the problem. Please see if there are any other problems you might encounter.
Here's my script with the cURL:
<?php
require "quimasetup.php";
$name = $_POST["name"];
$email = $_POST["email"];
$phone_number= $_POST["phone_number"];
$subject= $_POST["subject"];
$grade= $_POST["grade"];
$payment_id = $_POST["payment_id"];
$idclient = AVe40dqVhDDmGDbLhNEkH6G9eWyvgrqPrkKAucGv;
$sekret = ELQ595K9VZyfQcJuj7pw1yPVVv7OnNw;
$ch = curl_init("https://api.sandbox.paypal.com/v1/oauth2/token");
curl_setopt($ch,CURLOPT_HEADER,false);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_USERPWD, $idclient.":".$sekret);
curl_setopt($ch, CURLOPT_POSTFIELDS, "grant_type=client_credentials");
$result = curl_exec($ch);
curl_close($ch);
$json = json_encode($result);
$jsonn = json_decode($json);
$tkn = $jsonn->access_token;
$sql = "insert into craddle values('$name','$email','$phone_number','$subject','$grade','$payment_id','$tkn');";
if (isset($tkn)){
if(mysqli_query($connection,$sql)){
echo "<br><h3>one row inserted...</h3>";
}
else{
echo "Error in insertion...".mysqli_error($connection);
}
}
else{
var_dump($json);
var_dump($jsonn);
var_dump($tkn);
}
?>