It sounds as if Winzip can't find all three files in the same place. Normally when you create an archive and split the files up they are put into a specific directory. It may be that you need to recreate the directory structure that existed when the file was created.
Do you know that we're all in line for succession to the throne? Really? Well, if forty-eight million, two hundred thousand, seven hundred and one people died I'd be Queen.