WHMCS Sending Blank Backups in Email

[Mano]

Hii,

I have installed Vesta CP and only WHMCS (v 5.3.14 ) on my VPS.
Everything is fine, just one issue, the Backs generated via cron ( in whmcs ) , send me emails with database of 249 B , it should be 2.5 MB ( compressed sql file ).

I have made changes to my php.ini :

upload_max_filesize = 100 M
memory_limit = 768 MB
max_execution_time = 3000
post_max_size = 64 M

Still the issue is there.

The cron.php , is chmod 755 and admin folder is not password protected.

[skurudo]

And what's in exim log? Any errors?