webservice报错 “soapenv”是未声明的前缀

看下是否有这句话：
xmlns:soapenv=“http://schemas.xmlsoap.org/soap/envelope/”
如果是如下就会报以上的错
xmlns:soap=“http://schemas.xmlsoap.org/soap/envelope/”

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:tem="http://tempuri.org/">