Is there a reason why Maps will work with Edge but not with Wireless?

I notice that sometimes calling up maps of locations will only work when I turn off my wifi and use the edge network. The same is also true when accessing iTunes, and the weather. I have full strengh wifi signal and everything works quicker with wifi; but if I want maps to pull up a particular address, for example, I have to go to Edge. Is there a particular reason for this?