Sometimes get error 4600

Sometimes get error 4600

I'm trying to searchRecord using the Zoho CRM API and I sometimes get the following error:

Array ( [response] => Array ( [error] => Array ( [message] => Unable to process your request. Please verify whether you have entered proper method name,parameter and parameter values. [code] => 4600 ) [uri] => /crm/private/json/Contacts/searchRecords ) )

My problem is that sometimes everything works fine and sometimes I get this error

  1. define("TARGETURL", "https://crm.zoho.com/crm/private/json/Contacts/searchRecords");
  2. $parameter = array(
                'scope' => 'crmapi',
                'authtoken' => AUTHTOKEN,
                'selectColumns' => 'All',
                'criteria' => '(Account Name:'.$accountName.')',
                'fromIndex' => $fromIndex,
                'toIndex' => $toIndex
                );
  3. $ch = curl_init();
                curl_setopt($ch, CURLOPT_URL, TARGETURL);
                curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
                curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
                curl_setopt($ch, CURLOPT_TIMEOUT, 30);
                curl_setopt($ch, CURLOPT_POST, 1);
                curl_setopt($ch, CURLOPT_POSTFIELDS, $parameter);
                $result = curl_exec($ch);
                curl_close($ch);