Can we trust Deloitte & Touche?

Look at this page which shows 2006 federal election expenses by category and party. You'll that it shows zero for non-radio/tv advertising by the Conservative Party. This was recently amended by the Conservatives after they were questioned on it by Elections Canada (see Ottawa Citizen article here). This zero stands out like a sore thumb. There are only nine categories of expenses and every significant party has non-zero expenses in each category.

Deloitte & Touche were the auditors who approved the Conservative return back in May 2006. Months later they withdrew that opinion. How could they miss something so obvious? The next time I read an annual report of one of their clients, can I trust it?

To Deloitte & Touche:
This is not a trivial matter because there are serious questions currently about whether the Conservative Party illegally circumvented election spending limits in 2006.
I call on you to explain yourselves. Your brand is at stake.