Passing variable to child instance of make

hi,
I am trying to export a variable from the parent makefile to a child instance of my makefile within the same directory.

the relevant code in my parent makefile is:

libvar := $(notdir $(basename ../src/file1))
export libvar

.PHONY: library

library:
make -f makechild libvar=file1

in the child makefile, i.e. makechild, I have the following relevant code:
LVAR: =
fname := $(addprefix lib, $(LVAR))

but obviously I am missing something because echo $(fname) returns 'lib' (instead of libfile1)when I run the make command in the parent makefile.:wall:

can you pls. help me fix the code so I can export the value of libvar into LVAR

---------- Post updated at 11:10 PM ---------- Previous update was at 09:52 PM ----------

I just figured out I was making a dumb error,
I should keep the variable names the same in both the parent and child makefile.
so, in my child makefile, I renamed LVAR to libvar and it worked.
.....just in case anyone might be interested.