WCF Test Client not working with VS 2010 on Windows 7 64 bit

I am unable to use the WCF Test Client. I always get the following error.

Error: Cannot load reference assembly 'C:\Windows\Microsoft.Net\assembly\GAC_32\System.Data\v4.0_4.0.0.0__b77a5c561934e089\System.Data.dll'    
Cannot load file C:\Windows\Microsoft.Net\assembly\GAC_32\System.Data\v4.0_4.0.0.0_开发者_Python百科_b77a5c561934e089\System.Data.dll as an Assembly. Check the FusionLogs for more Information.
Could not load file or assembly 'file:///C:\Windows\Microsoft.Net\assembly\GAC_32\System.Data\v4.0_4.0.0.0__b77a5c561934e089\System.Data.dll' or one of its dependencies.
This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded.

I'm not having any luck finding a solution on google. I'm hoping that the stackOverflow hive brain can help.

Thanks.

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If I'm not mistaken, you need to add the runtime version setting in your app.config file's <configuration> element:

<startup>
  <requiredRuntime version="v4.0.30319" />
</startup>