There are several reasons your withdrawal might be rejected:
1) Invalid bank details entered. You may want to ensure you have updated the bank account information number, and not your card information number.
2) The withdrawal may have contained Cashback that was not earned by the user in a rare case of technical fault. In such cases, your withdrawal request will be reversed hence rejected.
Please contact our friendly HappyBag bot here if you have any further concerns and we will be at your assistance.