Check your data folder and see if there's a luafiles514/lua files/skillinfoz/skillinfolist.lua in there as well? Like not in the GRF's data folder, but in your Ragnarok's data folder.
If there is, you might want to rename/delete that one since it'll override your GRF's changes.
If that's not it, can you show what your data.INI looks like?