First of all, you can combine them all into a single declaration:
Second, if it's not working then it is because a) your stylesheet is cached (refresh your page a couple of times) or b) (most likely) because you have rules elsewhere in your stylesheet that allow set a bullet point on some ul or li that is of higher precedence than these rules.
The best way to determine if b is your issue is to open your web page in chrome, right click on your list item and select "Inspect element" - it will open a window that shows your HTML and, on the right side, shows you a list of CSS rules that are applied to it.
I've switched careers...
I'm NO LONGER a scientist,
but now a web developer...
I have noticed that I canít fully style the li tag either. For example I can put a border on it but I canít put a background color on it. I also canít set the height on my li tag. Its very frustrating. It is a big site I am trying to add a page too but I have never had this problem before. If it is B then i won't be able to do anything about that as maybe bullets are needed on that area of the site however how can i make it less priority? The original li and ul tags do not have bullet points.
Take a look at what I said doing - open your page up in chrome and right click and click "Inspect Element" - all the rules that your element is obeying, you may find that it's obeying a few rules from elsewhere in your stylesheet that you didn't expect it to.
For a primer in understanding CSS priorities (or specificities) this article on net tuts+ is quite good:
This was working this morning but when I clicked on one of my li links to test it everything went tits up. The hover is working but the li tag is now all of a sudden not reading from the CSS. Can anyone let me know why this is because its driving me nuts.