Residence visa outside UAE for more than 6 months?

My son, who is under the sponsorship of his father went home last June 2009. My son is 11 years old and we let him attend the school in our country for the meantime. Last October, because we understood that he should not be outside UAE for more than 6 months, we went to Jebel Ali Dubai immigration to ask what to do with his visa. We dont want to cancel his visa because we are sure that we will let him back in UAE. The receptionist in the immigration, who is a local guy, answered us that it's ok as long as the father's visa is still valid. The receptionist told us also that if we want to let our son return to UAE, we should bring his attested school record that he attended school in our country to show in the immigration that he really attended school in our place. Can we rely on this? Now is more than 6 months., maybe after 2 or 3 months we will let my son come back here in UAE. What is the rule about this issue? My friend from dubai told me that we will pay hefty penalty, is it true? i am so worried. Could anyone who understand the rules here tell us exactly what to do? Thank you.