I'll try my hand at playing devil's advocate hobo-jo;
The capex costs and cash operating costs are likely to be much higher by the time production starts due to inflation. The estimates I think were done late 2009 and since then the cost of most things has gone up. Ongoing capital costs will also reduce the profit margins.
On the upside: you forgot to include Interest earnings on cash held into the profit equation; and the silver price is now at $31/oz, which means by default the silver resource/reserves will increase in the next resource update to reflect the increased silver (&lead) price(s) :-)
CCU Price at posting:
65.6¢ Sentiment: Hold Disclosure: Held
