Vb.net 不明白为什么我的方法没有被调用

我的站点使用了几个文件处理程序，它们都有重复的代码。为了整理，我创建了一个通用基类，它们都可以继承：

Public MustInherit Class HandlerBase
Implements System.Web.IHttpHandler, System.Web.SessionState.IRequiresSessionState

Public ReadOnly Property IsReusable() As Boolean Implements IHttpHandler.IsReusable
    Get
        Return False
    End Get
End Property

Public Overridable Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest
        RequestHandler(context)
End Sub

Protected Overridable Sub RequestHandler(ByVal context As HttpContext)
    Select Case context.Request.HttpMethod
        Case "GET"
            GetFile(context)
        Case "POST"
            UploadFile(context)
        Case "DELETE"
            DeleteFile(context)
        Case Else
            context.Response.ClearHeaders()
            context.Response.StatusCode = 405
    End Select
End Sub

Protected MustOverride Sub GetFile(ByVal context As HttpContext)
Protected MustOverride Sub UploadFile(ByVal context As HttpContext)
Protected MustOverride Sub DeleteFile(ByVal context As HttpContext)

end class

我的两个处理程序在继承基类后工作得很好，但其中一个似乎根本没有启动。唯一的区别是此处理程序覆盖RequestHandler：

Protected Overrides Sub RequestHandler(ByVal context As HttpContext)
    Select Case context.Request.HttpMethod
        Case "GET"
            GetFile(context)
        Case Else
            context.Response.ClearHeaders()
            context.Response.StatusCode = 405
    End Select
End Sub

---

我访问处理程序，并且从未在base中调用ProcessRequest，也没有在RequestHandler中发现这是在fiddler中检查请求后的一个小错误：

Protected Overrides Sub DeleteFile(ByVal context As HttpContext
    Throw New NotImplementedException()
End Sub

缺少参数的结束括号。我将投票结束这场辩论