Originally Posted by fumje

Yes, typically having a cleared CPU reduces your SDC options. With CPU it looks for PZ space, which is usually less than space for whatever your original basis is. You can do a search for origin - destination and see which options show your economy basis (e.g., S, L, etc.) with availability. Then call and ask an agent to put you on that particular itinerary. If you don't know the basis, check your original receipt.