User blog:Marco the Marine Admiral/Why don't they activate Dragon Force?

Just looked back on the 7 Dragons' battle and I found something strange: None of the Dragon Slayers use Dragon Force!!! It's reasonable that Natsu, Gajeel and Wendy didn't use it because they can't activate it by will, but what about the other four? Why don't they use it? Do they have to hide it in their sleeves when facing real dragons? That's ridiculous!