I don't know what your debug is .. but here's what I always do for stuff like this..

use strict;
use warnings;

my ($x, $y, $z) = returner();


sub returner {
 my ($a, $b, $c);

 # define $a $b and $c


 # now for something I would throw in just for kicks
 # just before you return..

 defined $a or die("a not defined");
 defined $b or die("b not defined");
 defined $c or die("c not defined");

 return ( $a, $b, $c);

}
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Something else that might possibly help

use strict;
use warnings;

my ($x, $y, $z) = @{returner()};


sub returner {
 my ($a, $b, $c) =( undef, undef, undef);

 # define $a $b and $c


 # now we return one value only

 return [$a, $b, $c];

}
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