Ops, What is wrong?

Coding is just like experiments with unknow chemistry, you never know what will happen, you scratch you head and dont know why it doesn't work. You tried all different setting and combination, you collaborate with your buddies to find all possible solution. Until in a sudden momoent, you find the magic word "Avada Kedavra" to crack the problem. That is what we called Learning by Doing and Fun by Learning. ：）