Data::Dumper expects either a scalar or reference variable (Refer: DESCRIPTION section of Data::Dumper). You should pass it a reference to you structure. Remember to interpret $VAR1 as a reference to your structure. Using hippo's example:

#!/usr/bin/env perl 
use strict;
use warnings;
use Data::Dumper;

my @aktData = ([
    { foo => 'bar' },
    { foo => 'baz' }
]);

#print 'Array: ' . Dumper (@aktData);
print 'Array: ' . Dumper (\@aktData);
foreach my $data (@aktData) {
    print 'Element: ' . Dumper ($data);
}

OUTPUT:
Array: $VAR1 = [
          [
            {
              'foo' => 'bar'
            },
            {
              'foo' => 'baz'
            }
          ]
        ];
Element: $VAR1 = [
          {
            'foo' => 'bar'
          },
          {
            'foo' => 'baz'
          }
        ];
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The Dumper output clearly shows the problem he describes.