Not only that, but just to be sure, which package did you try? The Mandriva download page
shows half-a-dozen rpms for each version. Did you ensure that you got the one that matches your OS? You didn't perhaps download the source code package instead, did you?
This is why we need detailed information. Sometimes the mistake is in the simplest things, such as using the wrong package, and we need to be able to rule those out before moving on to more complex possibilities.
Did you try re-downloading the archive and trying again? It's possible that your download was corrupted the first time. Since your error message says it can't read the archive, this is a strong possibility.