Ruby on rails : uninitialized constant Zip::File::Create

Question

I'm trying to zip folder with rubyzip gem, I got this error :

uninitialized constant Zip::File::Create

this the method that create the zip :

def self.zip_pdf( report, paths )
    if File.exist?("#{Rails.root}/tmp/pdf/reports/#{report.reference}.zip")
      FileUtils.rm("#{Rails.root}/tmp/pdf/reports/#{report.reference}.zip")
    end

    directory = File.join( File.dirname( paths[0] ) )
    zipfile_name = File.join( File.dirname( paths[0] ) ) + '.zip'

    Zip::ZipFile.open( zipfile_name, Zip::ZipFile::Create ) do |zipfile|
      Dir[ File.join( directory , '*' ) ].each do |file|
        zipfile.add( file.basename( file ), file )
      end
    end

  end

I followed the doc but still don't know why it show that error !