is there any refusal of L visa this time?

Is there a refusal of L visa this time? Because I plan to invite my sister in China which I use to complete all the requirements needed includes: invitation letter with red ribbon, bank certificate copy, working permit photocopy .etc.. And it was informed to us by the agency who use to process the papers that it was refused. This incident happens twice already. We're asking for the reason but we didn't hear any answer from that agency.