Subscription probs with prime press

Hello,

I have both the subscribe via RSS and via e-mail icons on my blog. When the subscribe by e-mail is clicked a message comes up saying subscription via e-mail is not activated. But I have entered all my feedburner info, and when you click on subscribe by RSS, the option to subscribe via e-mail comes up (and works)
How can I get the e-mail link to work?
Many thanks,
Kate