From perldoc -f print:

    Note that if you're storing FILEHANDLES in an array
    or other expression, you will have to use a block
    returning its value instead:

        print { $files[$i] } "stuff\n";
        print { $OK ? STDOUT : STDERR } "stuff\n";
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So you need to put a block around the expression returning your filehandle:

    print { $Unique_DeviceType{$Unique_SN{$sn}->devicetype} } ...
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Since you're using the filehandle twice, though, you may as well just create a temp variable (in my opinion):

    my $fh = $Unique_DeviceType{$Unique_SN{$sn}->devicetype};
    print $fh ...
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