Command line burning non-empty disc, please help

Hello, i am newbie here and i encounter a problem of burning non-empty disc using nero 6.x command line tool. The software says “The disc is not empty” and prompt me to choose the options for further action. May i know how can i burn a non-empty disc using command line straight without system asking me to choose erase data or not? I dun wan to erase the other data since there are free place to burn also.

My command is below

nerocmd --write --drivename f --close_session --real --verify
–iso “Backup” “d:\backup*.zip”

May i know where it goes wrong?