Based on the existing question and answers, it appears that the reward you were expecting from 4 USDD has been set to 0 USDD and you have not received the USDD. This could be due to a number of reasons, such as a technical issue, an administrative error, or a change in policy. It is important to contact the relevant authorities to determine the exact cause of this issue. It may also be beneficial to review any recent changes to policies or procedures that could have caused this change. If the problem persists, it is best to contact customer service for further assistance.