You could try instead of calling the cron via wget - calling it via the file path..
e.g something like
/usr/bin/php -f /path/to/mydomain.com/public_html/cron.php
Also, another great module that I use to debug why my crons don't sometimes work is AOE Scheduler (https://github.com/AOEpeople/Aoe_Scheduler). Once installed there will be a timeline view inside of the Sytem menu of your admin. This will show you which tasks are going to run / have ran / will be run - along with any errors they produced.
If the timeline stays blank after 15 minutes or so then your cron isn't setup right on your server.
How to call cron.php is depend on your server.
Some wget, php, curl..etc.. many commands are capable of sending a output to a email address.. so you can try the command matching your server