Welcome to the Q&A Forum

0 page rank is based on the ToolBar PageRank?  Are you aware TBPR is both inaccurate and not updated more than a couple or at most a few times a year?  It's NOT the real PageRank your site has. Focus on continuing to do what you have been, and now emphasize quality link building.  Leave the TBPR concerns to others while you continue to get results and improve on them! Just a suggestion anyhow.