ngc file cancels remapping

I have remapped m300 to a ngc subroutine which returns the mill to its home position using these line in the ini file.

[RS274NGC]
PARAMETER_FILE = linuxcnc.var
USER_M_PATH = /home/shop/linuxcnc/subroutines
SUBROUTINE_PATH = /home/shop/linuxcnc/subroutines
REMAP=M300 modalgroup=10 ngc=m300

The routine works fine when called from mdi or called from within a hal file by called mdi_command-01, but once I load a new ngc file linuxcnc no longer can find the m300.ngc subroutine file. Anyone know why when I open a ngc file linuxcnc can not longer find the remapped subroutine.