So I get prompted to write the kana for 金. I've never quite understood what exactly it's asking for, but I'm guessing the on reading so I write: キン. Get a prompt saying "Close, but we're looking for the kana." So I figure, maybe it's the kun reading? I write かね. Again I get "Close, but we're looking for the kana." So I figure that maybe it should be きん. It's not.
What's up with that? This is not the only kanji with this issue, I might add -- a lot of them suffer from this.