母版页没有显示IPrincipal的扩展方法

Question

我遇到了问题而无法找到解决方案。

我有一个模块，其中包含一些IPrincipal的扩展方法：

<System.Runtime.CompilerServices.Extension()> _
Public Function CanCallGhostbusters(ByRef activeUser As IPrincipal) As Boolean
    Dim result As Boolean = False

    resultado = activeUser.IsInRole("GB\GhostBustersCaller") AndAlso ...

    Return result
End Function

代码在.aspx页面中运行良好：

Protected Sub Page_Load(ByVal s As Object, ByVal e As System.EventArgs) Handles Me.Load
    If User.CanCallGhostbusters Then
        //It works; cool!
    End If
End Sub

但它不在主页中工作;扩展方法没有出现在intellisense中。我试过了：

If HttpContext.Current.User.CanCallGhostbusters  Then
    //Error: CanCallGhostbusters is not a member of System.Security.Principal.IPrincipal
End If

Dim activeUser As System.Security.Principal.IPrincipal = HttpContext.Current.User
If activeUser.CanCallGhostbusters Then
    //Error: CanCallGhostbusters is not a member of System.Security.Principal.IPrincipal
End If

有什么想法吗？

谢谢！