D'oh... (hitting self upside head with Stupid Stick)

Got it - autocreate was failing because I nuked not only the file but also the original Maps directory that contained it. So just altering the filespec with that in mind did the right thing.

Truly idiot proof code might take the extra step of creating the target directory if necessary. I guess it depends on how much you're inclined to coddle idiots. ;-)

Anyway, thanks for the tip!