What's wrong is a different question than why doesn't it compile. Since you now know why it doesn't compile -- "what's wrong with it" is that it doesn't use a Templating system, such as HTML::Template. If you would use a templating system, then you would not need to embed your HTML into your Perl, and you would avoid having to use tools such as HEREDOCS which force your indentation to be non-uniform. At least HEREDOCS prevent you from having to escape your data, but there is a better way.

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)