Authentication/notarization of a Portuguese document by the Chinese Embassy in Portugal

I am Portuguese and I live in China for almost 5 years. My 5 year son is under my visa (Z). I always used the birth certificate given by the Portuguese authorities to get one for my son. Now the Chinese law changed and the Chinese authorities are asking me an authentication of my son's birth certificate by the embassy in Portugal. I went to my embassy here in Beijing and I got my son's birth certificate notarized but it seems that it is not enough. The authority is asking me to get a notarization/ authentication of my son's birth certificate by the Chinese Embassy in Portugal. I am trying to contact the Chinese embassy in Portugal but I cannot get through. Does anyone knows anything about this?