Problems sending with cron (phpList 3.0.12)

Hi, i have a PhpList 3.0.12 installed.
It does work manually fine with the “Process the queue” button, it sent every messages to every email address with no errors,
but when i set the cron with

/usr/bin/php -q /home/cpaneluser/public_html/lists/admin/index.php -p processqueue -c /home/cpaneluser/public_html/lists/config/config.php

it start the proccess, sent just 1 email and the it start to log
"Error sending email to myemailaddress Could not instantiate mail function."

What is diferent between manually sending and sending via cron?

maybe is it a hosting issue? this happend too with and old phplist version on the same server.
why it does work manually?

Thank you in advance

Hi, I have changed your title to make it a little clearer what the bug is about.

Your error is saying that the cron job cannot talk to your mail server.
Did you set the user for the cronjob to be ‘root’?

If you can, you should log into the command line of the server, and type that command, and see what errors occur.