sender build error log.txt

/Users/artifact/.rvm/rubies/ruby-1.9.2-rc2/bin/ruby extconf.rb
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
	--with-opt-dir
	--without-opt-dir
	--with-opt-include
	--without-opt-include=${opt-dir}/include
	--with-opt-lib
	--without-opt-lib=${opt-dir}/lib
	--with-make-prog
	--without-make-prog
	--srcdir=.
	--curdir
	--ruby=/Users/artifact/.rvm/rubies/ruby-1.9.2-rc2/bin/ruby
extconf.rb:9:in `require': no such file to load -- ruby_core_source (LoadError)
	from extconf.rb:9:in `<main>'