perl - Convert OWL Ontology to OBO -

i need convert owl ontology obo.

i've tried tool https://github.com/ontodev/robot/ output format isn't correct @ all, parts.

also obo-edit2 , protegé weren't able conversion.

lastly i've tried perl module http://search.cpan.org/~easr/ gives error

undefined subroutine &xml::parser called @ /usr/local/share/perl/5.14.2/obo/parser/owlparser.pm line 146.

and trying install xml::parser ends error.

could me convert ontology?

have tried https://github.com/owlcollab/owltools/?

and trying install xml::parser ends error.

what commands running install xml::parser? error? can install other perl modules ok same commands? ones require make?