What's wrong with my ER-V aug?Follow

I got an aug from DoN - Farcaster's Pumice Stone for Extended Range V (5). It says it's for a finger slot, and I inserted it into a ring. (I don't think that birdbath thing will let you put an aug into a slot that it won't work in.) Anyway, in a couple of zones, I've noticed that it doesn't seem to work. The two I've noticed so far are Plane of Earth and Plane of Fire.

It seems to work fine most of the time, and I have extended range on spells up to level 70.

Does anyone have any theories on why this would happen? Why in a few zones the ER would not work?