Backup fail with Cloud Core CCR1016-12G 6.1

Hi every one!

I`m tryng a script for make a system backup file of my router and then send to mail. Y this version “Cloud Core CCR1016-12G v6.1” when i make the following script :

/system backup save name=myrouter

it make a file called myrouter with 1920MiB (1,9GB)!!! it can`t be send for mail …

Can be a bug of this hardware/firmware/RouterOs Version?

Thanks.

I forget, more information: Current Firmware 3.09