Can not send direct message

[ZarchiMohammad]

I wrote this code:

and give this error:
{"errors":[{"code":32,"message":"Could not authenticate you."}]}

My permissions: Read, write, and direct messages
Also i have this error on TwitterAPIExchange class:
PHP Warning: rawurlencode() expects parameter 1 to be string, array given in .../TwitterAPIExchange.php on line 325

What am i do?

[Schiocco]

Same issue (PHP Warning: rawurlencode() expects parameter 1 to be string, array given). It doesn't work for arrays of arrays as post_field (in Postman you need to send the array as plan text(raw) body), if I do the same via this class, the signature broken and the error is {"errors":[{"code":32,"message":"Could not authenticate you."}]}