Queen – “The Trap” [Campaign 1, Mission 4]

Hello. I have the following problem: in the "Trap" mission, when I bring the hero to the checkpoint, "autosave" appears, after which a video should play showing Isabella being captured. Instead, I am returned to the map. I have explored the entire map, killed everyone, collected everything, but the result is the same. I thought the problem was with the disc, so I tried another one, but the situation is the same. I tried a third disc, and the result is the same. I suspect that the problem is still with the discs, because I once installed the game using 4 CDs with a bootable disc, and I didn't have this problem. Thank you very much for your help.