The comments in #883 by moondog are a very common scenario and should be considered as a possibility by any foreigner who is meeting resistance in getting what should be a routine Letter of Invitation for a business visa. However, PM information by jeanie suggests that she is encountering a different scenario due to nature of the product, and the Chinese agent's position is understandable once the complete context is known. It would seem that with this set of circumstances which I do not wish to detail further, obtaining a tourist visa is the way to go.