"mkgmap --name" is not working

One of the options in the command to generate maps is –mapname=name:
It sets the name of the map. Garmin maps are identified by an 8 digit number. The default is 63240001. It is best to use a different name if you are going to be making a map for others to use so that it is unique and does not clash with others.

I’m using following command to generate maps:
java.exe -Xmx6g -jar …/mkgmap/mkgmap.jar --output-dir=…/Belgium_map --max-jobs --index --description=OSM_Belgium --country-name=Belgium --country-abbr=BE --name-tag-list=“name:de,name,int_name” --series-name=OSM_Belgium --family-name=OSM_Belgium --area-name=Belgium --overview-mapname=OSM_Belgium --net --gmapsupp --tdbfile --route --add-pois-to-areas --road-name-pois=0x640a --draw-priority=25 --latin1 --make-opposite-cycleways --remove-short-arcs –mapname=200000000 -c template.args

Nevertheless the outcome tile-names are still in the default 63240001-range.

I did make a workaround via Excel to modify the ‘template.args’ (one of the files generated by the split command: “java.exe -Xmx4g -jar …/splitter/splitter.jar --output-dir=…/Belgium_split Belgium-latest.osm.pbf”) but I wonder why the –mapname argument is not working in the initial command line…

It would be nice to read a solution. Thx in advance…

Try --mapname (2 dashs).
Also 200000000 may be too large.