template class as a member

Hi

I get this error:

'MyClass' use of class template requires template argument list

My template class is as follows:

template <class T=int> class MyClass{
:
:
}

Another class has this template class as members.

#include "MyClass.h"
class B{
     private:
          MyClass a; //This line gives me the above mentioned error
    :
    public:
         B(MyClass in): a(in) {}
}

what am i doing wrong?

I wanted to do something like this:
MyClass<T>  a;


where the type of a i.e. the member  would be defined by what's passed in to the constructor. Is this possible?
 Can the type of a member be a template class, whose type parameter (T=int or float etc) be defined at compile time by what's passed in the constructor?