无法在wcf服务中的soapui标头中传递用户名和密码

<system.serviceModel>
  <bindings>
    <basicHttpBinding>
      <binding name="MyBinding">
        <security mode="TransportWithMessageCredential">
          <message clientCredentialType="UserName" />
        </security>
      </binding>
    </basicHttpBinding>
  </bindings>
  <services>
    <service name="MyService">
      <endpoint address="" binding="basicHttpBinding" bindingConfiguration="MyBinding" contract="IMyService" />
    </service>
  </services>
</system.serviceModel>

public class MyService : IMyService
{
  public void MyMethod()
  {
    // 获取传递的用户名和密码
    string username = OperationContext.Current.IncomingMessageHeaders.GetHeader<string>("Username", "Namespace");
    string password = OperationContext.Current.IncomingMessageHeaders.GetHeader<string>("Password", "Namespace");

    // 验证用户名和密码
    if (username == "admin" && password == "password")
    {
      // 执行相关操作
    }
    else
    {
      // 返回错误信息
    }
  }
}

<soapenv:Header>
  <Username xmlns="Namespace">admin</Username>
  <Password xmlns="Namespace">password</Password>
</soapenv:Header>