Re: cannot instantiate abstract class

I have a c++ applicaiton (as below) and I'm getting a linker error
that has me stumped. error C2259: 'myspace::PolicyImpl<T>': cannot
instantiate abstrace class.

If it's obvious to anybody what I'm doing wrong, please let me know.

   template < typename T >
   class Policy
   {
   public:
       virtual void RemoveAll( ClassA< T, myspace::Policy > *p ) = 0;
       virtual void Add( ClassB< T, myspace::Policy > *p ) = 0;
       virtual void Remove( ClassB< T, myspace::Policy > *p ) = 0;
   };

   template < typename T >
   class PolicyImpl : public Policy< T >
   {
   public:
       PolicyImpl(){};
       void RemoveAll( ClassA< T, myspace::PolicyImpl > *p )
       {
           //...
       }
       void Add( ClassB< T, myspace::PolicyImpl > *p )
       {
           //...
       }
       void Remove( ClassB< T, myspace::PolicyImpl > *p )
       {
           //...
       }
   private:
       //...
   };