I knew why... i put the baking powder before i add in water, not with plain flour. So tak jadi loh... baking powder with water before flour... can not "huat" loh. Didn't about it. But when recall back, i make a big mistake. Jing and Yang said "yak... not nice!"
Will redo to night. Yang birthday's tomorrow, i want to prepare few for him to bring to nursery.