Comment 1 for bug 1226200

In order to be able to really fix this bug, the package-structure of shimmer-themes would probably have to be changed, meaning that shimmer-themes would become a meta-package and all the themes separate packages. That mostly means more work for packagers.

While it is understandable that you want to use the latest version of Numix, there are two alternatives to your current route:
1) use the shimmer-themes daily PPA: https://launchpad.net/~shimmerproject/+archive/daily
2) just pull directly from git into your ~/.themes folder

At least for 13.10, this is a wontfix from my side (also because it's too late in the cycle).