namespace not recognized (even though it is there) in c# console application on Developers command prompt for VS2012

and this is error 

Program.cs(9,7): error CS0246: The type or namespace name 'Newtonsoft' could not
        be found (are you missing a using directive or an assembly reference?)
Program.cs(10,7): error CS0246: The type or namespace name 'PushSharp' could not
        be found (are you missing a using directive or an assembly reference?)
Program.cs(11,7): error CS0246: The type or namespace name 'PushSharp' could not
        be found (are you missing a using directive or an assembly reference?)
Program.cs(12,7): error CS0246: The type or namespace name 'PushSharp' could not
        be found (are you missing a using directive or an assembly reference?)