AddToRole and IdentityRole is not part of the model for the current context

I’m using Identity 2.1 to handle the user roles in my asp.net application. So far so good, i created new context extending from IdentityDBContext, extending the IdentityUser and IdentityRole to add a couple of new fields. However, whenever im trying to add a user to a specific role using the UserManager im getting The entity type IdentityRole is not part of the model for the current context.. So there seem to be something wrong with the user-role relationship, here is my code so far for reference:

Why does FireFox 3.6.8 not cache static contents from asp.net developer server?

I am working on a asp.net web site, like normal user, we use asp.net developer server during coding and testing.
Today, I found the firefox not cache any static file of my site, since our application is pretty big, it made page load time very slow.
I checked firefox about:cache, all the static file cache setting looks like