Tourist L type requirements (do I need confirmation letter of invitation from Chinese government)

I am Ogunyomi Musa Adisa from Nigeria, I was invited to China by my Kung Fu teacher who is a Chinese citizen with a Chinese local ID... I have the necessary documents with me to process the visa for my trip to PRC. But on getting to the Chinese consulate in Lagos, the lady on the seat told that I need a confirmation letter of invitation from the Chinese government... And she also said , they don't issue a tourist L type to Nigerian (how true is that?).

The following are the documents I presented at the consulate today....
1. application form (Form V.2013)
2. Two copies of different Invitation letter from my Teacher (One with full introduction of teacher and my details, the second one is the official invitation letter found on Chinese embassy website...
3. Coloured copy of my teacher's International passport data page and coloured copy of his Local ID.
4. Consent Letter from my sponsor (My Father)
5. Statement of account with 15,482 US DOLLARS.
6. Flight reservation documents (round trip)
7. Hotel reservation documents....

So... With all the above documents, I don't why I still need a letter from the Chinese government... After all, I'm not going there for a business, just a visit to my teacher in Dengfeng.

What can I do to help the situation? I'm thinking of going to the embassy at Abuja for clarifications...

I will be glad to read from you soon... Thanks,