I always getting this error. Not accept any number when i try

ammoammo@ammo-Mac-mini dmg-folder % create-dmg
--volname "Marvel's Spider-Man"
--window-size 600 400
--icon-size 128
--icon "Marvels Spider-Man Remastered.app" 200 200
--app-drop-link 400 200
--overwrite
--dmg-title "Marvels_Spider-Man_Remastered"
--out "/Volumes/QVO2/" \

Could not find 400