Got my MP's help and the reason are: study plan vague a d poorly documented (cos I didnt submit an accocceptance letter, which is not required for minors by the way). Secondly, due to Family and/or economic ties,incentive to remain in canada may be higher. I didnt include any economic ties for them.as they applied along with spouse who had all the economic ties attached. The children's applications were assessed separately from spouse. Its just getting confusing by the day.