I treid with easy_install lxml==2.1
and got following error
src/lxml/lxml.etree.c:120447: erreur: «XML_XPATH_UNDEF_PREFIX_ERROR" undeclared (first use in this function)
src/lxml/lxml.etree.c:120456: erreur: «XML_XPATH_UNKNOWN_FUNC_ERROR" undeclared (first use in this function)
src/lxml/lxml.etree.c:120465: erreur: «XML_XPATH_INVALID_OPERAND" undeclared (first use in this function)
src/lxml/lxml.etree.c:120474: erreur: «XML_XPATH_INVALID_TYPE" undeclared (first use in this function)
src/lxml/lxml.etree.c:120483: erreur: «XML_XPATH_INVALID_ARITY" undeclared (first use in this function)
src/lxml/lxml.etree.c:120492: erreur: «XML_XPATH_INVALID_CTXT_SIZE" undeclared (first use in this function)
src/lxml/lxml.etree.c:120501: erreur: «XML_XPATH_INVALID_CTXT_POSITION" undeclared (first use in this function)
src/lxml/lxml.etree.c:120698: erreur: «LIBXSLT_VERSION" undeclared (first use in this function)
src/lxml/lxml.etree.c:120709: erreur: «xsltLibxsltVersion" undeclared (first use in this function)
src/lxml/lxml.etree.c:120720: erreur: «__pyx_v_4lxml_5etree_XSLT_DOC_DEFAULT_LOADER" undeclared (first use in this function)
src/lxml/lxml.etree.c:120720: erreur: «xsltDocDefaultLoader" undeclared (first use in this function)
src/lxml/lxml.etree.c:120729: erreur: «__pyx_f_4lxml_5etree__xslt_doc_loader" undeclared (first use in this function)
error: Setup script exited with error: command 'gcc' failed with exit status 1
Do you have libxml2-dev and libxslt1-dev installed?
Also, support for gutsy ended over a year ago, you should really consider moving to hardy, which will be supported until April 2013