php - paypal express checkout dont work with sandbox -

i try integrate paypal express checkout using wizard https://devtools-paypal.com/integrationwizard/

all right if iam using real account, if enter sandbox account credentials script show no error: "setexpresscheckout api call failed. error message: error code: "

i have checked returns script's $resarray. i's ok:

array ( [token] => ec-2fp9406707909490n [timestamp] => 2016-01-27t14:52:37z [correlationid] => b6329a695bbf3 [ack] => success [version] => 93 [build] => 18308778 )

   $resarray = callshortcutexpresscheckout ($paymentamount, $currencycodetype, $paymenttype, $returnurl, $cancelurl);     $ack = strtoupper($resarray["ack"]);     if($ack=="success" || $ack=="successwithwarning")     {         redirecttopaypal ( $resarray["token"] );     }      else       {         $errorcode = urldecode($resarray["l_errorcode0"]);         $errorshortmsg = urldecode($resarray["l_shortmessage0"]);         $errorlongmsg = urldecode($resarray["l_longmessage0"]);         $errorseveritycode = urldecode($resarray["l_severitycode0"]);          echo "setexpresscheckout api call failed. ";         echo "detailed error message: " . $errorlongmsg;         echo "short error message: " . $errorshortmsg;         echo "error code: " . $errorcode;         echo "error severity code: " . $errorseveritycode;     } 

but if replace real sandbox credetials $resarray return empty array.

array ( ) setexpresscheckout api call failed. detailed error message: short error message: error code: error severity code:

what wrong?

you have check ssl certification on api call time. paypal change there api. experiment in sandbox. after june,2016 sandbox , live both credential not work without ssl. details check : https://devblog.paypal.com/upcoming-security-changes-notice/#tls