can't create Perl mapObj w/ filename

[Charlton Purvis]

Hi, folks:

For the life of me, I can't figure out what I'm doing wrong.  Whenever I
pump in a filename to create a mapObj, I get nowhere.  When I pump in an
empty filename, I'm allowed to continue.

use mapscript;
my $map_file = 'foo.map';
my $map = mapscript::mapObj->new($map_file);
$map->setExtent(0,0,0,0);

perl -c is OK.

At runtime:

Can't call method "setExtent" without a package or object reference at
./ms.pl line 4.

If I simply make $map_file = '';, everything works great.  But the deal is
that I want to read from an existing (and 100% working) .map file.

What the devil am I doing wrong?  Thanks for your help.

Charlton

mapserver-4.8.4