Return blank page when using gravity form api?

Following is my code:

$api_key = 'XXXXXX';
$private_key = 'XXXXXXXXXXXXXXXXXX';
$expires = strtotime( '+60 mins' );

// Insert data for Property Upload Form.
$route_1 = 'forms/8/results';
$string_to_sign_1 = sprintf( '%s:%s:%s:%s', $api_key, 'GET', $route_1, $expires );
$hash_1 = hash_hmac("sha1", $string_to_sign_1, $private_key, true);
$sig_1 = rawurlencode(base64_encode($hash_1));
$url_1 = 'https://www.abc.com.au/gravityformsapi/' . $route_1 . '?paging[page_size]=1000&api_key=' . $api_key .'&signature=' . $sig_1 . '&expires=' . $expires;
echo $url_1;

$response_1 = file_get_contents($url_1,false,NULL);

$test_1 = json_decode($response_1);
print_r($test_1);exit;

it returns a blank page, when i hit on my $url_1, it’s just redierect on some other page.
if i click on ‘https://www.abc.com.au/gravityformsapi/forms/‘, it still shows blank data.


Source: stackoverflow-php