On most laptops the fn+arrows keys have extra functions (home, end, PgUp, PgDn). This keyboard has the fn-key but the hardware is not configured to use the fn+arrow combination.
The fn-key cannot be changed by software. The KB7221W keyboard (which is part of the KM7321W keyboard/mouse set) can be updated through an firmware.
@DELL: Please add the fn+arrow key functions like configured on your laptops?