I have just tested the disk on my real Amiga 1200.
everything is working
I have received messages from some argentinian Amiga users from the argentinian Amiga forum. They told me demo 2 is corrupted but the other two were ok, using WinUAE basica A500 config...
I will try to re-upload the file, using a different floppy drive on my PC (im using Catweasel to convert them but i guess the newer floppy drives are not very friendly with Catweael)
Thanks for the feedback anyway guys!