How to create a Task associated with an Account by using PHP SDK?

How to create a Task associated with an Account by using PHP SDK?

i would like to ask some problem like this.
when i want to create a task associated with Account infomation. so i write these codes.

  2. $rest = \ZCRMRestClient::getInstance();
  3. $record = $rest->getRecordInstance("Tasks", null);
  4. $record->setFieldValue("Subject", "example title");
  5. //...
  6. $responseIns=$record->create();

  8. $createdrecord = $responseIns->getData();
  9. $account = \ZCRMJunctionRecord::getInstance('Accounts', $data['account']);
  10. $createdrecord->addRelation($account);

then. i catch a error message " the relation name given seems to be invalid"
why ? 

ZOHO CRM REST API v2.0 using PHP SDK
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