If Unable to add reference file in visual studio 2010

If you are adding the reference file in visual studio. 2010 and after adding it show the error change the .net 4 client framework to .net 4 framework.
Select <project name>property (eg. Data property) from project in menu bar, then you find this window and select “application tag” and change the” target framework” from “.NET 4 Framework  client profile” to “.NET 4 Framework”.