Onimushawarlord

I have used the TM take down and the TM mega kick on my charmander but they dont show up on his move set. Everytime I teach him a move, I get an alert saying he was taught the move but it never prompts me to forget a move and it never shows up as one of his moves. This also happened when I went to the move re learner, I paid the money to re learn fire fang. But it doesnt show up in charmanders moves nor does it ask me to forget the move. Am I doing something wrong or what should I do? I dont want to keep wasting money.