Music On Hold Upgrade Broken

|| Getting this error when upgrading the module: ||

Please confirm the following actions:

* Music on Hold will be upgraded to

I click process… then (in the lovely orange box)

Warning: fopen(/etc/asterisk/musiconhold_additional.conf) [function.fopen]: failed to open stream: Permission denied in /var/www/html/admin/modules/music/install.php on line 21

Warning: fwrite(): supplied argument is not a valid stream resource in /var/www/html/admin/modules/music/install.php on line 23
Cannot write to file ()

Check that the file /etc/asterisk/musiconhold_additional.conf has the right permission and owner. The upgrade program cant open the file for writing.
Are you using Trixbox?