Membership.GetUser -> 成员资格不包含 'GetUser' 的定义。我错过了什么?

Membership.GetUser -> Membership doesn't contain a definition for 'GetUser'. What have I missed?

MembershipUser newUser = Membership.GetUser(CreateUserWizard1.UserName);

我在 GetUser 下看到一条红线,当我将鼠标悬停在它上面时,会出现一条消息:

Membership doesn't contain a definition for 'GetUser'

当我点击 GetUser 下面的小破折号时,我得到:

Generate method stub for 'GetUser' in 'Membership

我错过了什么?

ASPX:

<asp:CreateUserWizard ID="CreateUserWizard1" runat="server" OnCreatedUser="CreateUserWizard1_CreatedUser" >
    <WizardSteps>
        <asp:CreateUserWizardStep ID="CreateUserWizardStep1" runat="server">
        </asp:CreateUserWizardStep>
        <asp:CompleteWizardStep ID="CompleteWizardStep1" runat="server">
        </asp:CompleteWizardStep>
    </WizardSteps>
</asp:CreateUserWizard>

后面的代码:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.Security;

public partial class SignUp : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    protected void CreateUserWizard1_CreatedUser(object sender, EventArgs e)
    {
        MembershipUser newUser = Membership.GetUser(CreateUserWizard1.UserName);
        Guid newUserId = (Guid)newUser.ProviderUserKey;
    }
}

问题是由于存在同名 Membership 的 class。已经定义的方法没有方法定义 GetUser.
代码工作实际需要的是调用 classMembership 的完整命名空间来区分两者;已经定义的一个和预期的一个。意向者可参考: System.Web.Security.Membership

而不是这个: MembershipUser newUser = Membership.GetUser(CreateUserWizard1.UserName);

使用这个:
MembershipUser newUser = System.Web.Security.Membership.GetUser(CreateUserWizard1.UserName);