I'm guessing you are not using the latest version of Date::Manip 6.46. You could try

$delta=Delta_Format(DateCalc($start_date_parsed,$end_date_pa
+rsed),'',"%dt"); # changed from %dv
[download]

but if you did upgrade you could use the OO interface like this

use strict;
use Date::Manip;

my $start_date = '8/4/2014';
my $end_date   = '8/15/2014';
print "$start_date to $end_date \n";

my $date1 = new Date::Manip::Date;
my $date2 = $date1->new_date();
my $err1 = $date1->parse($start_date);
my $err2 = $date2->parse($end_date);

while ($date1->cmp($date2) <= 0) {
  print $date1->printf("%m-%d-%Y")."\n";
  $date1->next_business_day(1);
}
[download]

poj