Class forward declaration with RealView Compiler

Hello,

i have a question related to Realview Compiler V3.0.
Is the forward declaration of a class not supported or
is it a mistake of me?
Please look the example below:

class clsB;     // Forward Declaration  Not Working


class clsA
{
  public:
        clsA();         // Constructor

        clsB  oB;       // Compiler error:  #70: incomplete type is not allowed
};




class clsB
{
  public:
        clsB();         // Constructor
};

Thank you
Eugen