Firstly, check for any typos in the registration you've entered.
If it looks ok, you contact the seller of the vehicle and check the registration number with them.
If the registration number you are trying is correct, then we are unable to carry out a check. We do not have a record of this vehicle in our database.
This may be because the vehicle has recently had a plate change.
In this instance, you should contact the seller to get the previous plate and carry out the check on this. It may take a little while for the plate change to become effective.