The back link tracker is just that (primarily a back link tracker). The Page Rank (and Pages in URL for that matter) are secondary, and are only updated when there is new back link data.
There is significant delay for visual PR; what you see on the toolbar. It is often very different from your actual PR.
The one he's talking about is the one that shows charts of your historical PageRank (and other stuff) here: http://www.digitalpoint.com/tools/keywords/
Recheck two or three times, it may possible sometimes,even if it shows same, then try some other PR Checker Tools.
PR have 2 type Real Pagerank and Toolbar Pagerank. Mostly user used Google Toolbar or any other toolbar for see the site Page Rank. But, toolbar show only virtually PR not real Page Rank. Pagerank is very difficult algorithm. In short the more websites are linking to your domain the higher pagerank will your site get. This is real pagerank.
Pagerank used in the algorithm for determining sites rank in the SERPS. Pagerank updates daily. Historically, every three months. The buying and selling of signature links amongst its users The link sales forum – Plenty of guideline breaking links get sold in that forum every day. DP COOP – The Digital Point Coop link exchange network is still active and spamming Google’s search results to this day.