web.config encryption

Hi Guys,
 
I tried aspnet_regiis.exe ausprobiert to encrypt my connectionString
The web.config I just copied into C:\Windows\Microsoft.NET\Framework\v2.0.50727\Test\
and run the tool with
C:\Windows\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe -pe connectionStrings-app /Test
 and I also tried
 
C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\test

Mit C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe -pe "connectionStrings" -app "/Test" 

The error is always:

"The configuration for virtual path '/Test' and site 'Default Web Site' cannot be
opened.
Specified argument was out of the range  of valid values.
Parameter name: site
Failed!"

Do you guys have an idea how to fix that?
greetings,
polynaux 
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