Time Machine won't back up my other external hard drive!

[phsycology]

Hey

I just got round to setting up time machine. But, as well as the external hard drive that time machine uses, I use another to store other files on; time machine will not back up this hard drive! It has automatically appeared on the exclude list in time machine's preferences, though does not give me the option to include it. How do I do this?

Thanks,
Arran

[phsycology]

Anyone????