Looking at PEM's price relative to the price of zinc going back...

Looking at PEM's price relative to the price of zinc going back as far as Jan 2006 I believe that we are under priced by about 40% - 50%. When Zn started moving up in early 2006 and hit 90c/lb, PEM was around $1. Zinc reached a high of $2+ in late 2006 then began to fall. It fell to about todays price (90c/lb+) in may 2008. PEM's price was then around 90c. The price of Zn today is 90c/lb+ and the share price is below 50c. Add to that....lower mining costs (current costs are below 60c/lb now V's more than $1/lb previously) and we should be valued at about $1+.
So where is my arithmetic wrong??

Luck
Q