Throwaway incomplete downloads option greyed out

I am trying to have Hazel watch a file and delete incomplete files after a certain period of time, however the option is greyed out. How can i fix this?

It should be enabled if the folder in question is set to be a download folder for some program (Safari, Mail, Firefox, etc). If this is the case and the option still isn't available, then post what program you are using as well as what version of Hazel and OS X.

Note that there is a known issue if you are running 10.4.11 as it switched to Safari 3. That was somewhat of a surprise to me so the current version of Hazel will not detect that case properly (fix is in the works).

I have it set as the incomplete folder for both transmission and shakespeer. It is also greyed out for the folder that complete downloads are transfered to.

Ah, neither of those programs are specifically supported. I haven't even heard of shakespeer before this.

As for Transmission, it doesn't really have a way of marking the files themselves as incomplete. Instead it has the ability to use separate folders such that when the download is complete, it will move it to a special folder for complete downloads. If you do this and want to purge files out of your folder of incomplete downloads, you can have Hazel monitor that folder and set up a rule to trash files after some amount of time. You can base it on date added or date modified, depending on your needs.

Let me know if you need any more clarification on this.