Pr 6 is a tough nut to crack, they have to see you actively buidling, expanding fresh content everyday and links to relevant high pr pages. They've been holding off on giving out PR thought...in all honestly there's no reason for them to.
Put a couple of millions on the table & you'll have it in 3 months... Did you really think it was that easy? Everybody wants the same as you.
Get backlink from 1 quality PR8 website with 20 below OBL. You will get PR6 or PR7 in the next pr update.
It's not an easy task to get PR6 at one go. you must know PR is calculated once every 3-4 months. Give ample time for your website to gain more quality backlinks. Patience is all you need to see higher PR.
its important to remember that your site will show as having no PR until the next toolbar update happens. - You cannot change this