[help] how to activate the harddisk drive in webmsx from start.

please, help.
i would like to activate the hard disk drive in webmsx from start. that is, activate the hard drive by default.

for example i opened the source code, and i found in line 217,

WMSX = {
... ... (abbreviation) ... ...
PRESETS: "",

So, i changed "PRESTS: "" to "PRESETS: "HARDDISK".
It seemed to work, because the hard drive icon appears at start.
BUT, if i load an image disk and type "files" on disk basic console, the error" Bad drive name" appears.
what' wrong with me?

thanks.