Work visa for a cultural group

Hi we are group of professional dancers from srilanka. we have been invited for 1 year contract with one of the famous park in china. They have already sent me work petmit and invitation letters for our 7 people. One of the letter from culture department. As you mentioned in above I want to know can i apply work type entry permit (z) with this letter from culture department, but our embassy is not accepting that. They need the work permit from the labour ministry. But in the above mentioning as one of the following documents. So please give your advise for get our Z type.
Thank you