Redmine

Hello,

I just installed remdine on my synology and I would like to use its pdf export functionality.
However, when I try to used it, I get the following error:
=======================LOG START=============================
Internal error

An error occurred on the page you were trying to access.
If you continue to experience problems please contact your redMine administrator for assistance.

Back
=======================LOG END=============================

The webrick server also generates the following log:
=======================LOG START=============================

Processing IssuesController#index to pdf (for 192.168.1.11 at 2011-03-11 10:41:49) [GET]
Parameters: {"format"=>"pdf", "project_id"=>"interval-tree", "action"=>"index", "controller"=>"issues"}

Iconv::InvalidEncoding (invalid encoding ("ISO-8859-1", "UTF-8")):
lib/redmine/export/pdf.rb:92:in `initialize'
lib/redmine/export/pdf.rb:92:in `new'
lib/redmine/export/pdf.rb:92:in `Cell'
lib/redmine/export/pdf.rb:137:in `issues_to_pdf'
app/controllers/issues_controller.rb:95:in `index'
app/controllers/issues_controller.rb:90:in `index'
/opt/lib/ruby/1.8/webrick/httpserver.rb:104:in `service'
/opt/lib/ruby/1.8/webrick/httpserver.rb:65:in `run'
/opt/lib/ruby/1.8/webrick/server.rb:173:in `start_thread'
/opt/lib/ruby/1.8/webrick/server.rb:162:in `start'
/opt/lib/ruby/1.8/webrick/server.rb:162:in `start_thread'
/opt/lib/ruby/1.8/webrick/server.rb:95:in `start'
/opt/lib/ruby/1.8/webrick/server.rb:92:in `each'
/opt/lib/ruby/1.8/webrick/server.rb:92:in `start'
/opt/lib/ruby/1.8/webrick/server.rb:23:in `start'
/opt/lib/ruby/1.8/webrick/server.rb:82:in `start'

Rendering /volume1/redmine/redmine-1.1.1/public/500.html (500 Internal Server Error)
=======================LOG END=============================

Any help would be welcome,
thanks in advance,
cedric.