After I add any of the DDR interfaces to a custom board in Base System Builder, the GUI no longer allows me to add further peripherals, and the DDR peripheral is not added to the design. Additionally, the Back button does not allow me to return to the first screens of the wizard.
To work around this issue, do not add the DDR peripheral during BSB; add it directly to the design later in XPS.
This issue is fixed in EDK 8.2i. which is scheduled for release in June 2006.