I was issued a single entry business visa for China but my schedule changed

so I wasnt able to use it within 3months it was issued. My company originally asked me to apply for a 1 year multiple entry one but was only given the minimum 3mos allowed because it will be my first time to come to China.
Now my schedule is finalized for October, will I need a separate document to explain why I wasnt able to use it when I apply for a new single entry business visa?
Thank you very much.