Why can't I enter sun holiday codes?

Excuse me, I'm having some trouble entering my sun holiday codes. Could you please clarify why this might be happening? Is there a specific format or process I need to follow to input the codes correctly? Perhaps there's a technical issue on the system's end that's preventing me from proceeding. Alternatively, could there be a limitation or restriction on my account that's causing this issue? I'd appreciate any insight you could provide to help me resolve this matter. Thank you.