使用界面时出现vb.net错误

“Error 19 Class ‘LegacyRouteHandler’ must implement ‘Function
GetHttpHandler(requestContext As RequestContext) As IHttpHandler’ for
interface ‘System.Web.Routing.IRouteHandler’.”

从这段代码：

Public Class LegacyRouteHandler
    Implements IRouteHandler
    Public Function GetHttpHandler(requestContext As RequestContext) As IHttpHandler
        Return New LegacyHandler(requestContext)
    End Function
End Class

我正在清楚地实现GetHttpHandler,任何想法我为什么会收到此错误？

...) As IHttpHandler Implements IRouteHandler.GetHttpHandler
'                    ^

VB.NET不会自动将函数连接到它们的接口定义,如C#.