It seems the PHP array only has 5 items if that is what is displaying?
What does the actual HTML output of the page look like? Go to the web page and right click and view source.
Post up the HTML and I'll take a look for you.
The second thing it might be that I have come accross in the past is the articles in the marquee are wrapping round onto a second line that isn't shown, so you end up with 5 articles on the first line, and 5 on the second, just you cannot see the second line at all as the overflow is generally hidden.