I just installed the latest XML::SAX, ran your code, and it produced the following results:

Starting document...
Starting element greeting
characters: Hello, world!
Ending element greeting

with Perl 5.6.0 - you might need to upgrade or use merlyn's suggestion.

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)