Problem while setting cron job on ubuntu 16.04

[konstantinosdms]

Here is my cron job on ubuntu 16.04 32bit
30 01 * * 7 export DISPLAY=:0 && '/home/konstantinos/FreeFileSync/FreeFileSync /home/konstantinos/Desktop/tomahawk_batch.ffs_batch'
but when i sudo mount -a i get the following error:
mount: /etc/fstab: parse error: ignore entry at line 15.

Any suggestion?

[Menel]

'mount -a' producing fstab errors has nothing to do with crontab edits.

'mount -a' mounts all devices in fstab.
fstab is the table of filesystems. Browse fstab and see if you have an error at line 15.

[konstantinosdms]

The error points to this command.When I comment it it does not display any errors.Also the above command when I run it from shell,does not start the gui!!!