php和深度关联数组错误

I have following code

$array_store='maxbounty/maxBounty.json';
$test = $array_store->return[0]->entries[1]->value;
echo $test;

Here the file maxBounty.json has following format.

stdClass Object ( [return] => Array 
( [0] => stdClass Object ( [entries] => Array 
( [0] => stdClass Object ( [key] => LAUNCH_DATE [value] => 2017/02/10 )
 [1] => stdClass Object ( [key] => COUNTRIES [value] => US ) 
[2] => stdClass Object ( [key] => CONTEXTUAL_TRAFFIC_ALLOWED [value] => Y )... and so on

But i am getting following error

Notice: Trying to get property of non-object in C:\wamp\www\couponcactusapis\test2.php on line 5

How can i print the value of LAUNCH_DATE , COUNTRIES and CONTEXTUAL_TRAFFIC_ALLOWED ?

Any idea please. THANKS.