use Win32;
use Win32::OLE;
use Win32::OLE::Enum;

# louder errors
Win32::OLE->Option(Warn => 3);
...
my $Enum = Win32::OLE::Enum->new($Recipe->Placements);
while (defined(my $placement = $Enum->Next)) {
    Win32::MsgBox($placement->PlacementPart->{Refdes});
}

# - or -

use Win32::OLE qw/ in /;
for my $placement (in $Recipe->Placements) {
    Win32::MsgBox($placement->PlacementPart->{Refdes});
}