You need to wait for the next tool bar update which is happening in another 2 to 3 months time. Mean while, try to attract relevant incoming links to your site. This is the only way to increase your PR
They probably missed the update. The backlinks were probably acquired after the snapshot period. Continue building links, and you should see an increase at the next update...
Google know your PR, dont worry, they are just not updating the green bar. Why do you want PR by the way ?
Check for one of the live google page rank tools which checks your page rank across a number of Google data centers. This will give you a more accurate picture of your PR.
keep adding content and get some links...if you don't mind paying for them, get some in the link sales area of this forum. And don't worry about PR, its really not that big of a deal.
Wait for some time. At the next update you will see your ranking. But you need to accumulate lots of backlinks from high PR sites with similar content to see anything meaningful.
Current PR is a snapshot around end of March, so if you didn't get your PR by end of march you won't see it until next update (in about 2 months).
did you do build back links to your blog. if no that's reason. get more back links to your blog dont just expect it will gain back link by it owns. If you do have back links, get some more and wait for next PR update. wish you a good luck. ^^