error with gmake: overriding macros

[Nolan Ed-P1840C]

the attached makefile works with basic make routine on my unix box and
gmake.

make    -f makefile.simdif mul0 ; # works
gmake   -f makefile.simdif mul0 ; # works

however, when I try to override the textmacro TIMING (defined in the
makefile) 

make TIMING=min -f makefile.simdif mul0; # make command properly overrides
the internally defined textmacro and executes the make.
gmake TIMING=min -f makefile.simdif mul0 ; #-- gmake command fails ERROR 2

 <<makefile.simdif>> 

I have tried many different debug options and spent a bunch of time trying
to figure out why.  to no avail.. Is this a legitimate bug?


gmake -ver
GNU Make version 3.79, by Richard Stallman and Roland McGrath.
Built for hppa2.0n-hp-hpux11.00
Copyright (C) 1988, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99
        Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.

makefile.simdif
Description: Binary data