Can't write to an xlsx spreadsheet

[fabian....@gmail.com]

Hey Guys,

How can I write to an xlsx spreadsheet? This is my code (as instructed in the webiste):

require 'rubygems'

require 'roo'

include Roo  # If I don;t put this, I get an error...

s = Excelx.new('test.xlsx')      # creates an Openoffice Spreadsheet instance

s.default_sheet = 'Backup'

s.set_value(14, 4, 'TEST')

And this is the error I get:

C:/Ruby193/lib/ruby/gems/1.9.1/gems/roo-1.11.1/lib/roo/excelx.rb:536:in `block in read_labels': undefined method `split' for nil:NilClass (NoMethodError)

Ideas? I already did quite a lot of googling without luck...

Thanks!

Fabian