altera 添加ddr2 出现如下错误，什么原因 ？

Warning (12069): Ignored assignment(s) for "mem_odt[0]" because "mem_odt" is not a bus or array
Error (12014): Net "DDR2:DDR2U|mem_dq[15]", which fans out to "DDR2:DDR2U|DDR2_controller_phy:DDR2_controller_phy_inst|mem_dq[15]", cannot be assigned more than one value
Error (12015): Net is fed by "DDR2:DDR2U|DDR2_controller_phy:DDR2_controller_phy_inst|mem_dq[15]"
Error (12015): Net is fed by "GND"
Error (12015): Net is fed by "DDR2:DDR2U|mem_dq[15]"
Error (12015): Net is fed by "DDR2:DDR2U|DDR2_controller_phy:DDR2_controller_phy_inst|DDR2_phy:DDR2_phy_inst|mem_dq[15]"
Error (12015): Net is fed by "DDR2:DDR2U|DDR2_controller_phy:DDR2_controller_phy_inst|DDR2_phy:DDR2_phy_inst|DDR2_phy_alt_mem_phy:DDR2_phy_alt_mem_phy_inst|mem_dq[15]"

从错误描述来看，就是你安排了多个连接给mem_dq[15]。请注意你的信号或者管脚安排。当然，也有可能是Quartus版本的bug。