Fortigate Automatic backup Problem

Hi  we use  fortigate 200E . i have to get automatic backup and i set :

edit "DAILYBACKUP" set interval 86400 set repeat 0 set start auto set script "execute backup config ftp dailybackup.conf 192.168.1.3 test1 test2"

that 192.168.1.3 is my ftp server ip address , test1 is usename and test2 is password

but there is a problem about send configuration file to ftp server . error message is :

Connect to ftp server 192.168.1.3  ... Send config file to ftp server via vdom root failed.

Command fail. Return code 5

Does anyone know how can i solve this problem

Thank you