求助！！！急！急！急！在线等！

我用K7芯片在ISE生成一个MAC核，例子工程编译没有错误，但是我在例子工程之中包了一层我自己的顶层就出现了这个错误，怎么解决？
Place:1073 - Placer was unable to create RPM[BUFIO_RPMs] for the component U1/U1/trimac_fifo_block/trimac_block/rgmii_interface/bufio_rgmii_rx_clk of type BUFIO 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 TIEOFF_X0Y214 where we must place BUFIO U1/U1/trimac_fifo_block/trimac_block/rgmii_interface/bufio_rgmii_rx_clk 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:
   BUFIO   U1/U1/trimac_fifo_block/trimac_block/rgmii_interface/bufio_rgmii_rx_clk
   IOB33V   RGMII_RXC_0<0>
Pack:1654 - The timing-driven placement phase encountered an error.