this might help... from this site

http://www.investopedia.com/articles/02/110802.asp

The Important Dates of a Dividend
There are four major dates in the process of a company paying dividends:

• Declaration date– This is the date on which the board of directors announces to shareholders and the market as a whole that the company will pay a dividend.
• Ex-date or Ex-dividend date– On (or after) this date the security trades without its dividend. If you buy a dividend paying stock one day before the ex-dividend you will still get the dividend, but if you buy on the ex-dividend date, you won't get the dividend. Conversely, if you want to sell a stock and still receive a dividend that has been declared you need to sell on (or after) the ex-dividend day. The ex-date is the second business day before the date of record.
• Date of record– This is the date on which the company looks at its records to see who the shareholders of the company are. An investor must be listed as a holder of record to ensure the right of a dividend payout.
• Date of payment (payable date) – This is the date the company mails out the dividend to the holder of record. This date is generally a week or more after the date of record so that the company has sufficient time to ensure that it accurately pays all those who are entitled.

Why All These Dates?
Ex-dividend dates are used to make sure dividend checks go to the right people. In today's market, settlement of stocks is a T+3 process, which means that when you buy a stock, it takes three days from the transaction date (T) for the change to be entered into the company's record books.

As mentioned, if you are not in the company's record books on the date of record, you won't receive the dividend payment. To ensure that you are in the record books, you need to buy the stock at least three days before the date of record, which also happens to be the day before the ex-dividend date.



As you can see by the diagram above, if you buy on the ex-dividend date (Tuesday), which is only two days before the date of record, you will not receive the dividend because your name will not appear in the company's record books until Friday. If you want to buy the stock and receive the dividend, you need to buy it on Monday. (When the stock is trading with the dividend the term cum dividend is used). But, if you want to sell the stock and still receive the dividend, you need to sell on or after Tuesday the 6th.