According to the ASX (http://www.asx.com.au/research/dividends/process.htm)
The ex dividend date occurs four business days before the company's Record Date. To be entitled to a dividend a shareholder must have purchased the shares before the ex dividend date. If you purchase shares on or after that date, the previous owner of the shares (and not you) is entitled to the dividend.
I am confused, if someone sells their shares on the Ex Dividend date, with a 3 day settlement wouldn't the new owner of the shares be on the company register by the record date (4 business days after the ex dividend date)??