How can I reattach data to my Fedora 15 torrent in Transmission (mac)?

-I have already downloaded over half of the Fedora 15 DVD, and my internet is relatively slow compared to most people, so I don't want to restart the download. Transmission tells me that there is "No data found"



How can I reattach the data that I already downloaded so it will pick up in the same place?

I'm using a mac btwjust restart it wait