Must I declare or not SHARED_EXPORT for an inner class ?

[tonnot]

I want to have an inner class contained by a parent class in a DLL.
I have
define MYCLASS_ASHARED_EXPORT Q_DECL_EXPORT at global .h for the dll
and :
class MYCLASS_ASHARED_EXPORT My_class_a into the h.file of the class.

Inside the My_class_a I have an inner class : inner_class
I can compile the dll, but I dont now hot to use the innerclass.

I can write My_class_a::inner_class.mymethod, QT understand it, but I cant build the program because I have undefined reference to My_class_a::inner_class.mymethod.

Must I write SHARED_EXPORT for the inner class ? How ?
I think It can be a basic c++ question (or not...) but I need help.
Thanks

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Added after 1:

I answer myself....

I have to declare the inner class with SHARED_EXPORT , that's all.
Thanks.