Well, if you are Windows, the OS will mess with some of those combos. It registers most of the number pad keys with shift as things like HOME instead of shift+key. Your best bet in that case is to remap the keys to something else or use different modifiers. (One thing I’ve seen is to set them to F13-24 which shouldn’t conflict with anything.)
If you are on a mac, then you can try this solution to get it working: