TypeError (no marshal_dump is defined for class Mutex)

[Phil Eun]

I’m using ruport 1.6.3, rails 2.3.3, ruby 1.9.1 and when I try to
render a pdf via the call:

render_grouping data, options.to_hash.merge(:formatter => pdf_writer)

I get the following error:

TypeError (no marshal_dump is defined for class Mutex):
/usr/lib/ruby/gems/1.9.1/gems/transaction-simple-1.4.0/lib/
transaction/simple.rb:129:in `dump'
/usr/lib/ruby/gems/1.9.1/gems/transaction-simple-1.4.0/lib/
transaction/simple.rb:129:in `start_transaction'
/usr/lib/ruby/gems/1.9.1/gems/transaction-simple-1.4.0/lib/
transaction/simple/group.rb:102:in `block in start_transaction'
/usr/lib/ruby/gems/1.9.1/gems/transaction-simple-1.4.0/lib/
transaction/simple/group.rb:102:in `each'
/usr/lib/ruby/gems/1.9.1/gems/transaction-simple-1.4.0/lib/
transaction/simple/group.rb:102:in `start_transaction'
/usr/lib/ruby/gems/1.9.1/gems/pdf-writer-1.1.8/lib/pdf/
simpletable.rb:396:in `render_on'
ruport (1.6.3) lib/ruport/formatter/pdf.rb:301:in `block in
draw_table'
/usr/lib/ruby/gems/1.9.1/gems/pdf-writer-1.1.8/lib/pdf/
simpletable.rb:109:in `initialize'
ruport (1.6.3) lib/ruport/formatter/pdf.rb:293:in `new'
ruport (1.6.3) lib/ruport/formatter/pdf.rb:293:in `draw_table'
ruport (1.6.3) lib/ruport/formatter/pdf.rb:97:in `build_table_body'

I’m following the example found in ‘The Ruport Book’ (http://
ruportbook.com)

Has anyone seen this or have any other issues trying to get ruport to
work with ruby 1.9.1?
Thanks.