what is meant by authorized Chinese departments

I have a letter from a Chinese company in Beijing asking me to visit them for establishing business. But the Chinese cConsuate did not accept my application, although accompanied by officia letter from the company and a copy of the company business registration. how to get authorized Chinese Departments documents?

(2) (F) Visa: Issued to an applicant who is invited to China on a visit, on a study or lecture, business tour, for scientific-technological and cultural exchanges, for short-term refresher course or for job-training, for a period of no more than six months. To apply for an F Visa, the official invitation letter from authorized Chinese departments is required.