Google PR1's one site but keeps other at PR0

[SEO]

Okay, so I have 2 sites. Site A has been up and running since last September 2008.Site B has been up and running since last Febuary 2009Site B is a PR1 and Site A is a PR0.Now both sites have pretty much the same link exchange going on. So whenever one site is linking, the other site is as well.What I don't understand is that google wont PR my site yet. Why? I had a google adsense acount on the site, but it got banned. Does Adsense have anything to do with the PR?