为什么HTTP::Message::decodable抱怨“不能将未定义的值用作哈希引用”?

我得到一个 Can't use an undefined value as a HASH reference 尝试调用时出错 HTTP::Message::decodable() 使用aptitude软件包管理器在Debian Lenny OS上安装Perl 5.10/libwww。我真的被卡住了,希望你能帮我个忙。

错误如下:

 Can't use an undefined value as a HASH reference at (eval 2) line 1.
at test.pl line 4
main::__ANON__('Can\'t use an undefined value as a HASH reference at 
enter code here`(eval 2)...') called at (eval 2) line 1
HTTP::Message::__ANON__() called at test.pl line 6

use strict;
use HTTP::Request::Common;
use Carp;
$SIG{ __DIE__ } = sub { Carp::confess( @_ ) };

print HTTP::Message::decodable();