D2 ntsc usa could work on dreamcast pal with utopia?

[verenacchio]

sorry for my bad english.
i've just buy an original copy of D2.
the format of the game is ntsc usa.
i've a dreamcast pal unmodified, and so i use utopia boot.
the game work perfectly, but D2 is a multidisks-game (4 gd rom)
when the game ask me to change disk, for example from 1 to 4, the dreamcast could recognize the new disk that i've put in.
why? the utopia boot reach to start the game, but when i've to change the disk to continue the adventure the message says: "this is not a dreamcast game, please insert D2 disk".
so, utopia boot don't work with imported multidisks-game? or is there a solution for an unmodified dreamcast?
thanks