asp.net - Why does this give me a YSOD? -

I have added the last two lines on web.config in response to wagging fingers from the asafaweb () report on my site:

  & lt; System.web & gt; & Lt; Compilation debug = "false" targetFramework = "4.0" /> & Lt; HttpRuntime targetFramework = "4.0" /> & Lt; Enable httpRuntime VersionHeader = "false" /> & Lt; CustomArder mode = "RemoteOnly" default redirect = "~ / Buibo" /> & Lt; /system.web>   
 ... but due to YSOD, "enableVersionHeader" had to comment.  
 This information has been given to me by asafaweb due to which I had to cause that extra:  
  The address you entered is unnecessarily exposing the following feedback header Which reveals its own choice of web platform: Server: Microsoft-IIS / 7.5 by X-Power: ASP.NET X-Espnet-version: 4.0.30319 This information silences information by configuring the application to return unnecessary headers. Is there And to identify the underlying structure makes it much more difficult.   
 Then I have two "httpRuntime" rows in one:  
     
 ... but asafaweb still gives me a single warning, so what's the problem?  
 UPDATE  
 Based on the link in the comment, I added it:  
  
 ... to Web.config, but then I found this YSOD:  
  HTTP Error 500.19 - Internal Server Error The requested page can not be accessed because the page's related configuration data is invalid.    
 
 
 Take a look at this discussion: