The link supplied when you purchased it expires after a certain time period.
You can sign into WinCustomize and click the link below and you will get a list download links for each of your purchases.
It could be that your dream is corrupt so you should download a new copy of it. You may also need the serial number so copy it so you can paste it into the reg box when you run the dream.
https://www.wincustomize.com/myaccount.aspx?reg