quartus中出现 Error:cannot be assigned more than one value

quartus中出现 Error:cannot be assigned more than one value
请问,在quartus仿真验证中出现 Error:cannot be assigned more than one value 该如何解决?
实例：
Error:Net "bianmaqi_2:U2|miao[7]~0",which fans out to "bianmaqi_2:U2|Mod0",cannot be assigned more than one value
Error:Net is fed by "bianmaqi_2:U2|shijian:d2|miao[7]"
Error:Net is fed by "bianmaqi_2:U2|miao[7]"
Error:Net "bianmaqi_2:U2|miao[4]~3",which fans out to "bianmaqi_2:U2|Mod0",cannot be assigned more than one value
Error:Net is fed by "bianmaqi_2:U2|shijian:d2|miao[4]"
Error:Net is fed by "bianmaqi_2:U2|miao[4]"
Error:Net "bianmaqi_2:U2|miao[3]~4",which fans out to "bianmaqi_2:U2|Mod0",cannot be assigned more than one value
Error:Net is fed by "bianmaqi_2:U2|shijian:d2|miao[3]"
Error:Net is fed by "bianmaqi_2:U2|miao[3]"
Error:Net "bianmaqi_2:U2|miao[2]~5",which fans out to "bianmaqi_2:U2|Mod0",cannot be assigned more than one value
Error:Net is fed by "bianmaqi_2:U2|shijian:d2|miao[2]"
Error:Net is fed by "bianmaqi_2:U2|miao[2]"
Error:Net "bianmaqi_2:U2|miao[1]~6",which fans out to "bianmaqi_2:U2|Mod0",cannot be assigned more than one value
Error:Net is fed by "bianmaqi_2:U2|shijian:d2|miao[1]"
Error:Net is fed by "bianmaqi_2:U2|miao[1]"
Error:Net "bianmaqi_2:U2|miao[0]~7",which fans out to "bianmaqi_2:U2|Mod0",cannot be assigned more than one value
Error:Net is fed by "bianmaqi_2:U2|shijian:d2|miao[0]"
Error:Net is fed by "bianmaqi_2:U2|miao[0]"
是不是实例化的问题?