C++ / CLI XML XmlObjectSerializer abstract class

I am using .net 3.5. In a C# project i can access XmlObjectSerializer as

System.Run开发者_JAVA技巧time.Serialization.XmlObjectSerializer

but in C++ / CLI project i can not able to use that class as

 System::Runtime::Serialization::XmlObjectSerializer

What is the problem? Why i can not able to reach that class under C++/CLI?

Best Wİshes

I sounds simply like a missing assembly reference to assembly:  System.Runtime.Serialization (in System.Runtime.Serialization.dll)