Not sure if it is the same thing or not, but when I tried to install something (I don't remember what it was) with Yum once, it kind of screwed up and didn't install the packages. After messing with my system for a while (finding out what versions where correct and wrong, all were still the old versions), I typed the same command that I typed in the first-place. Doing this caused Yum to check the repo, check the dependencies, and then it wanted to download the packages again. As soon as it tried, it saw that it already had those packages in its cache, and proceeded to install them.
So, if your packages don't install, it might be worth it to just try running yum again.