StandardError for ibm_dbadapter

I need help here , recently i want to recreate my project , database
shift to db2 9.1

I update my rails to 2.1.0 , ruby 1.8.6 , rake 0.8.1 , ibm_db
0.9.4,successfully connected , but have this error:

undefined method `StandardError' for
#<ActiveRecord::ConnectionAdapters::IBM_DBA
dapter:0x30417a0>
d:/ruby/lib/ruby/gems/1.8/gems/ibm_db-0.9.4-x86-mswin32/lib/
active_record/connec
tion_adapters/ibm_db_adapter.rb:783:in `tables'
d:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.0/lib/active_record/
connection_a
dapters/abstract/schema_statements.rb:313:in
`initialize_schema_migrations_table
'
d:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.0/lib/active_record/
migration.rb
:387:in `initialize'
d:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.0/lib/active_record/
migration.rb
:357:in `new'
d:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.0/lib/active_record/
migration.rb
:357:in `up'
d:/ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.0/lib/active_record/
migration.rb
:340:in `migrate'
d:/ruby/lib/ruby/gems/1.8/gems/rails-2.1.0/lib/tasks/databases.rake:99
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
also , whenever  i retrieve data  from my db , the same error show up