System.Xml in visual studio not working

I am trying to process XML with C# in Visual Studio and it will not allow me to import System.Xml. I looked at other posts about this problem and this was usually caused by misspelling System.Xml to System.XML. I have the right spelling so I am not sure what is causing me problems. I looked under references and there is no System.Xml and I am using Visual Studio 2013 The error message was

Error 1 The type or namespace name 'Xml' does not exist in the namespace 'System' (are you missing an assembly reference?)


Do I have to download System.Xml?