The most common cause of this problem is due to the browser's cache. The browser keeps copies of the most recently visited pages on your local hard disk. If you are not seeing the changes to your page, then the browser is likely getting the copy stored in the cache as opposed to the new version on the server. This problem is easily fixed by either forcing the page to reload, or clearing your browser's cache manually. The method of doing both of these tasks will vary depending upon the browser you are using.