Failure with std::unique_ptr in STL container

Storage of following class fails:

std::unordered_map<std::string,std::unique_ptr<TAttLine>>

I also add more complex example - derived class.
At some point ROOT complains that dictionary for std::unique_ptr<TAttLine> missing, but if I try to add such class into LinkDef - dictionary generation exit with error:

Error: It is not necessary to explicitly select class unique_ptr<TAttLine,default_delete<TAttLine> >. I/O is supported for it transparently.

Error in <ACLiC>: Dictionary generation failed!