Are you a "no-reply" Blogger???
I was and I didn't even realize it! It's not easy to find how to fix it on your own, but I came across this great tutorial that walks you through how to fix the problem.
Fix your no reply blogger status here.
It's hard to interact (and win fun giveaways) if no one can reach you. With the big SMS giveaway day coming up, make sure you're not a no reply blogger too!
Special thanks to Fluster Buster for posting this great info!