CIED

I will start working on getting my Police Clearance Certificate from the CEID office very soon after I have been accepted at a semi-governmental company. Although the job is not administrative but still I got a bad feeling that it will be rejected. Can you please provide any insight about how to handle this situation to increase the success rate?TIA!
I got my Clearance Certificate rejected without declearing any reason....Can anyone help me in anyway? Thanks.
Think positive