What could have caused my Thai visa application rejection in HCMC and how can I improve my next application in Laos?

Hi, my DTV application got rejected in HCMC yesterday. 5 working days, no additional documents asked.

I applied as Thai soft power, here are what I submitted:

1.Passport first page

2.Photo

3. Vietnam visa and stamp, Hotel confirmation, Boarding pass

4. Asset certificate for 1 year shows every month had more than 1M THB (under financial products category, not deposit), A copy of Chinese ID card(I thought only the ID number was needed, didn’t do the translation), Two motorcycle green book copies (I have tow motorcycles in Chiangmai)

5. Thai soft power 6 months course related documents.

And about the basic information I had put in, for the home address part, I thought they were asking for the address I am staying in Vietnam, so I wrote my hotel address and one more address in my country (China)

Now I want to try again in Laos, hope I can get some advice about what I did wrong.

Thank you