Проблема подключения DDR к Spartan 6 Опции

[maxics]

DDR подключен к третьему банку Spartan-6 (xc6slx75-2fgg484c) . В MCB подключил DDR к проекту. Сделал UCF. На этапе map возникает ошибка по всем внешним сигналам. Привожу одну из них:

Place:1073 - Placer was unable to create RPM[IOB_RPMs] for the component
mcb3_dram_dq<10> of type IOB for the following reason.
The reason for this issue:
Some of the logic associated with this structure is locked. This should cause
the rest of the logic to be locked. A problem was found at site PAD376 where
we must place MCB u_DDR/memc3_wrapper_inst/memc3_mcb_raw_wrapper_inst/samc_0
in order to satisfy the relative placement requirements of this logic. It is
not legal to place this component in this site. The following components are
part of this structure:
IOB mcb3_dram_dq<10>
IODELAY
u_DDR/memc3_wrapper_inst/memc3_mcb_raw_wrapper_inst/dq_15_0_data.iodrp2_DQ_10

В чём может быть проблема?