Documentation setup errors on Debian 5 during gem installations

Hello!

I have an Ubuntu 10.04 system (my development system) and a Debian 5
system (my production system).
When installing gems on Ubuntu everything works really fine, but on
the Debian 5 system the same gems come up with errors during the
documentation setup. Why does that happen (below some examples)?

Best regards,
Kai

Rails 3 installation:
ERROR: While generating documentation for builder-2.1.2
... MESSAGE: Unhandled special: Special: type=17, text="<!-- HI -->"
... RDOC args: --ri --op /var/www/vhosts/comparilla.org/.rvm/gems/
ruby-1.8.7-p299@rails3/doc/builder-2.1.2/ri --title Builder -- Easy
XML Building --main README --line-numbers --quiet lib CHANGES Rakefile
README doc/releases/builder-1.2.4.rdoc doc/releases/builder-2.0.0.rdoc
doc/releases/builder-2.1.1.rdoc --title builder-2.1.2 Documentation

gem install mysql:
Installing ri documentation for mysql-2.8.1...

No definition for next_result

No definition for field_name

No definition for field_table

No definition for field_def

No definition for field_type

No definition for field_length

No definition for field_max_length

No definition for field_flags

No definition for field_decimals

No definition for time_inspect

No definition for time_to_s

No definition for time_get_year

No definition for time_get_month

No definition for time_get_day

No definition for time_get_hour

No definition for time_get_minute

No definition for time_get_second

No definition for time_get_neg

No definition for time_get_second_part

No definition for time_set_year

No definition for time_set_month

No definition for time_set_day

No definition for time_set_hour

No definition for time_set_minute

No definition for time_set_second

No definition for time_set_neg

No definition for time_set_second_part

No definition for time_equal

No definition for error_errno

No definition for error_sqlstate
Installing RDoc documentation for mysql-2.8.1...

No definition for next_result

No definition for field_name

No definition for field_table

No definition for field_def

No definition for field_type

No definition for field_length

No definition for field_max_length

No definition for field_flags

No definition for field_decimals

No definition for time_inspect

No definition for time_to_s

No definition for time_get_year

No definition for time_get_month

No definition for time_get_day

No definition for time_get_hour

No definition for time_get_minute

No definition for time_get_second

No definition for time_get_neg

No definition for time_get_second_part

No definition for time_set_year

No definition for time_set_month

No definition for time_set_day

No definition for time_set_hour

No definition for time_set_minute

No definition for time_set_second

No definition for time_set_neg

No definition for time_set_second_part

No definition for time_equal

No definition for error_errno

No definition for error_sqlstate