Thanks to Google for giving blog network Pagerank back, in fact this blog Pagerank decreased from 3 to N/A after I place a paid link from LW, yeah I know what makes my blog Pagerank decreased after removing that paid link, this is ironic. You know what I mean? Hmm when you want to place paid link on your main blog, you must be careful with any search engine crawlers, especially Google crawlers. So how to place paid link safely? I don't know how, I'm a white SEO person. Honestly it's hard to place paid link that crawler doesn't identify it as a paid link, before my Pagerank back to 3, I visited Matt Cutts' blog and request "private" Pagerank reconsideration to him, and I think it's never works. Ha ha LOL.
How to make your blog Pagerank back? Off course check your layout and all links. Who knows Google crawler judge your blogroll as a paid links. Maybe you can move that links to inner page, if you use blogspot just move your links to a new post, and don't forget to link that post at homepage. Got that? For example this link exchange page is linked on tab menu below that Adsense ads unit.