Why can't I call Macro of Macro library in custom class?

I created ‘A’ class, and I created Macro Library setting that parent class is ‘A’ class.
And I tried to use macro from that created Macro Library in ‘A’ class’ EventGraph. but, I couldn’t use that macro.
I can only use that macro on derived class of ‘A’. Why? Why can’t I use that macro in ‘A’ class?