Are you running the first cron job with the colons?
/usr/local/cpanel/bin/jailshell: -c: /home/my_username/public_html/folder/file.php"
Try removing the colons and also the double quote at the ends of the cron jobs.
If they are child element of parent div, you need to add space before child elements.
$( id + 'textarea') will look for an element with id '#letter_abstracttextarea'
$( id + ' textarea') = '#letter_abstract textarea' will look for child textarea element whose parent element has this specific id.