php - simplexml_load_file not working with variable but works with string -

i trying connect crm (pardot).

i have create url necessary call xml:

//this log in , print api key (good 1 hour) console $rz_key = callpardotapi('https://pi.pardot.com/api/login/version/3',  array(     'email' => 'myemail@email.com',     'password' => 'password',     'user_key' => '032222222222222b75a192daba28d'  )  );  $number_url  = 'https://pi.pardot.com/api/prospect/version/3/do/query'; $number_url .= '?user_key=032222222222222b75a192daba28d'; $number_url .= '&api_key='; $number_url .= trim($rz_key); $number_url .= '&list_id=97676';  $ike = simplexml_load_file($number_url); print_r($ike); 

now code returns :

simplexmlelement object ( [@attributes] => array ( [stat] => fail [version] => 1.0 )   [err] => invalid api key or user key )  

however, if echo $number_url, , copy , paste url browser, loads wonderfully. if copy , paste same echoed url simplexml_load_file works wonderfully also. must use variable, because api key 1 hour. ideas?

the rest of code here, provided pardot :

<?php /**  * call pardot api , raw xml response  *   * @param string $url full pardot api url call, e.g. "https://pi.pardot.com/api/prospect/version/3/do/query"  * @param array $data data send api - make sure include api_key , user_key authentication  * @param string $method get", "post", "delete"  * @return string raw xml response pardot api  * @throws exception if unable contact pardot api or went wrong  */ function callpardotapi($url, $data, $method = 'get') { // build out full url, query string attached. $querystring = http_build_query($data, null, '&'); if (strpos($url, '?') !== false) {     $url = $url . '&' . $querystring; } else {     $url = $url . '?' . $querystring; }  $curl_handle = curl_init($url);  // wait 5 seconds connect pardot api, , 30 // total seconds complete curl_setopt($curl_handle, curlopt_connecttimeout, 5); curl_setopt($curl_handle, curlopt_timeout, 30);  // https only, please! curl_setopt($curl_handle, curlopt_protocols, curlproto_https);  // verify ssl - should never changed. 2 = strict verify curl_setopt($curl_handle, curlopt_ssl_verifyhost, 2);  // return result server return value of curl_exec instead of echoing curl_setopt($curl_handle, curlopt_returntransfer, 1);  if (strcasecmp($method, 'post') === 0) {     curl_setopt($curl_handle, curlopt_post, true); } elseif (strcasecmp($method, 'get') !== 0) {     // perhaps delete?     curl_setopt($curl_handle, curlopt_customrequest, strtoupper($method)); }  $pardotapiresponse = curl_exec($curl_handle); if ($pardotapiresponse === false) {     // failure - timeout or other problem. depending on how want handle failures,     // may want modify code. folks might throw exception here. might     // log error. may want return value signifies error. choice yours!      // let's see went wrong -- first @ curl     $humanreadableerror = curl_error($curl_handle);      // can http response code     $httpresponsecode = curl_getinfo($curl_handle, curlinfo_http_code);      // make sure close handle before bug out!     curl_close($curl_handle);      throw new exception("unable complete pardot api call $url -- curl error: \"".                             "$humanreadableerror\", http response code was:     $httpresponsecode"); }      // make sure close handle before bug out!     curl_close($curl_handle);      return $pardotapiresponse; }  //this log in , print api key (good 1 hour) console   $rz_key = callpardotapi('https://pi.pardot.com/api/login/version/3',   array(     'email' => 'myemail@email.com',     'password' => 'mypassword',     'user_key' => '********************'   ) );  $number_url  = 'https://pi.pardot.com/api/prospect/version/3/do/query'; $number_url .= '?user_key=****************'; $number_url .= '&api_key='; $number_url .= $rz_key; $number_url .= '&list_id=97676';  $number_url = preg_replace('/\s+/', '', $number_url);  $ike = simplexml_load_file($number_url); print_r($ike);  ?>