I can't be certain, but I suspect the problem is in the last print statement you show.
print $my_graph->plot(\@data)->$format();
The plot function returns a GD object, for example:
my $gd = graph->plot(...);
my $format = $my_graph->export_format; 
print header("image/$format"); 
binmode STDOUT;
print $gd->gif;

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In reply to Re: Creating a Histogram by cdarke
in thread Creating a Histogram by arguelje

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