PowerShell Error: Cannot write configuration file

Im getting the below error when trying to use the Set-WebConfiguration cmdlet at a file level. It seems to work fine on the site level, please help. 

Error: Cannot write configuration file

+ CategoryInfo : NotSpecified: (:) [Set-WebConfiguration], DirectoryNotFoundException
+ FullyQualifiedErrorId : System.IO.DirectoryNotFoundException,Microsoft.IIs.PowerShell.Provider.SetConfigurationCommand

Set-WebConfiguration system.webServer/httpRedirect "IIS:\Sites\Default web site" -location index.html -Value @{enabled="true";destination="http://google.com";exactDestination="true";childOnly="false";httpResponseStatus="Permanent"} -verbose