My 17yo son is applying for a job working with children, so is having a DBS check, which requires him to get his ID documents verified at our local Post Office. His passport and driving license scanned ok, but his birth certificate was rejected, with no explanation. It has been folded in the past, so has a light crease in the middle. Is that likely to be the reason? (He said it was being scanned by a tablet that looked like an i-pad or similar).