http://www.cic.gc.ca/english/helpcentre/answer.asp?qnum=1145&top=29
"Note: You do not have to meet the funds requirement if you were invited to apply under the Canadian Experience Class.
The system currently asks all applicants to provide a proof of funds document. If you don’t need to provide proof of funds, you must upload a letter explaining either that you have been invited to apply under the Canadian Experience Class, or that you have a valid job offer."