As I said, I used to get that too. I had to re-download Mavericks about 3 times or so for it to actually work.
It is usually caused by improper/corrupt download. Or.. That's what happened to me. So try and re-download Mavs. First you have to delete the Mavs app from Applications or wherever it is stored in your PC. If you have it at more that one place, delete all those files and only then attempt the re-download!