Ms. Joe, I have the same experience as you, I submit all required documents for business visa, however, I was refused to get a visa, when I ask the reason, the visa officer didn't tell me anything.

Then I get the information from website of a Chines embassy,
PS: Whether a visa is to be issued or not, and what type of visa to be issued shall be decided by Consular officers in the light of China's relevant laws and regulations. Application may be refused without detailed explanation.

If you don't give me explanation, how can I know what things I should correct?

Hello Mr. JIm,

Thanks for your reply, I got my passport this morning and no one can tell me the reason why they refused my application. On the visa counter, they just told me that no one can answer my question why they have to refused. Is that really a chinese law not to give any informations if they will refused you? How will I know the reason then? Is it still possible for me to apply again?