Should have been proofread

I often see the word of being written when it should be have, as in he should of known better, but I do believe this is the first time I have ever seen have written when it should be of. From "James resigns as B.C. NDP leader" on CBC News online on December 6, 2010. Click the image to enlarge it. The text of the above excerpt has been revised since I employed the screen capture, but the error remains.