jekyll-liquid-pygments-error

      Generating...   Liquid Exception: private method `sub' called for nil:NilClass in _posts/2014-01-02-welcome-to-jek
yll.markdown
/home/thorkh/.gem/ruby/1.8/gems/jekyll-1.4.2/bin/../lib/jekyll/tags/highlight.rb:77:in `add_code_tags': private method `
sub' called for nil:NilClass (NoMethodError)
        from /home/thorkh/.gem/ruby/1.8/gems/jekyll-1.4.2/bin/../lib/jekyll/tags/highlight.rb:57:in `render_pygments'
        from /home/thorkh/.gem/ruby/1.8/gems/jekyll-1.4.2/bin/../lib/jekyll/tags/highlight.rb:45:in `render'
        from /home/thorkh/.gem/ruby/1.8/gems/liquid-2.5.4/lib/liquid/block.rb:106:in `render_all'
        from /home/thorkh/.gem/ruby/1.8/gems/liquid-2.5.4/lib/liquid/block.rb:93:in `each'
        from /home/thorkh/.gem/ruby/1.8/gems/liquid-2.5.4/lib/liquid/block.rb:93:in `render_all'
        from /home/thorkh/.gem/ruby/1.8/gems/liquid-2.5.4/lib/liquid/block.rb:82:in `render'
        from /home/thorkh/.gem/ruby/1.8/gems/liquid-2.5.4/lib/liquid/template.rb:124:in `render'
        from /home/thorkh/.gem/ruby/1.8/gems/liquid-2.5.4/lib/liquid/template.rb:132:in `render!'
        from /home/thorkh/.gem/ruby/1.8/gems/jekyll-1.4.2/bin/../lib/jekyll/convertible.rb:88:in `render_liquid'
        from /home/thorkh/.gem/ruby/1.8/gems/jekyll-1.4.2/bin/../lib/jekyll/convertible.rb:150:in `do_layout'
        from /home/thorkh/.gem/ruby/1.8/gems/jekyll-1.4.2/bin/../lib/jekyll/post.rb:259:in `render'
        from /home/thorkh/.gem/ruby/1.8/gems/jekyll-1.4.2/bin/../lib/jekyll/site.rb:239:in `render'
        from /home/thorkh/.gem/ruby/1.8/gems/jekyll-1.4.2/bin/../lib/jekyll/site.rb:238:in `each'
        from /home/thorkh/.gem/ruby/1.8/gems/jekyll-1.4.2/bin/../lib/jekyll/site.rb:238:in `render'
        from /home/thorkh/.gem/ruby/1.8/gems/jekyll-1.4.2/bin/../lib/jekyll/site.rb:39:in `process'
        from /home/thorkh/.gem/ruby/1.8/gems/jekyll-1.4.2/bin/../lib/jekyll/command.rb:18:in `process_site'
        from /home/thorkh/.gem/ruby/1.8/gems/jekyll-1.4.2/bin/../lib/jekyll/commands/build.rb:23:in `build'
        from /home/thorkh/.gem/ruby/1.8/gems/jekyll-1.4.2/bin/../lib/jekyll/commands/build.rb:7:in `process'
        from /home/thorkh/.gem/ruby/1.8/gems/jekyll-1.4.2/bin/jekyll:77
        from /home/thorkh/.gem/ruby/1.8/gems/commander-4.1.5/lib/commander/command.rb:180:in `call'
        from /home/thorkh/.gem/ruby/1.8/gems/commander-4.1.5/lib/commander/command.rb:180:in `call'
        from /home/thorkh/.gem/ruby/1.8/gems/commander-4.1.5/lib/commander/command.rb:155:in `run'
        from /home/thorkh/.gem/ruby/1.8/gems/commander-4.1.5/lib/commander/runner.rb:402:in `run_active_command'
        from /home/thorkh/.gem/ruby/1.8/gems/commander-4.1.5/lib/commander/runner.rb:78:in `run!'
        from /home/thorkh/.gem/ruby/1.8/gems/commander-4.1.5/lib/commander/delegates.rb:7:in `run!'
        from /home/thorkh/.gem/ruby/1.8/gems/commander-4.1.5/lib/commander/import.rb:10
        from /home/thorkh/bin/gems/bin/jekyll:19