Start App On Bootup – Debian

I have a ts3.desktop file in my /usr/share/applications folder that I want to run on system boot.

I have typed the following commands which don’t work

crontab -e

Then in the editor, I typed

@reboot gtk-launch ts3 /usr/share/applications

Then I pressed ctrl+o to save it. I reboot and nothing happens, the application doesn’t start. What can I do?

UPDATE: After I put these commands in, I did the following command to help you guys with troubleshooting this issue, see below.

$ crontab -l
no crontab for server
$ps -ef | grep cron | grep -v grep
root         532      1   0 21:35 ?                 00:00:00 /usr/sbin/cron -f