No complexity chart on embedded database

ActiveRecord::StatementInvalid (ArgumentError: Comparisons between 'INTEGER' and 'CHAR (UCS_BASIC)' are not supported. Types must be comparable. String types must also have matching collation. If collation does not match, a possible solution is to cast operands to force them to the default collation (e.g. select tablename from sys.systables where CAST(tablename as VARCHAR(128)) = 'T1'): SELECT * FROM snapshots WHERE (snapshots.id IN ('1'))  ORDER BY created_at ASC):
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/activerecord-jdbc-adapter-0.6/lib/active_record/connection_adapters/jdbc_adapter.rb:571:in `log_no_bench'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/activerecord-1.15.6/lib/active_record/base.rb:418:in `execute'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/activerecord-1.15.6/lib/active_record/base.rb:418:in `find_by_sql'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/activerecord-1.15.6/lib/active_record/base.rb:418:in `find_every'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/activerecord-1.15.6/lib/active_record/base.rb:418:in `find'
    /software/sonar-1.2/lib/sonar-web/app/models/service/jfreechart.rb:34:in `complexity_chart'
    /software/sonar-1.2/lib/sonar-web/app/controllers/chart_controller.rb:38:in `complexity_distribution_chart'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/actionpack-1.13.6/lib/action_controller/base.rb:1101:in `send'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/actionpack-1.13.6/lib/action_controller/base.rb:1101:in `perform_action'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/actionpack-1.13.6/lib/action_controller/filters.rb:696:in `call_filters'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/actionpack-1.13.6/lib/action_controller/filters.rb:688:in `perform_action_with_filters'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/actionpack-1.13.6/lib/action_controller/benchmarking.rb:66:in `perform_action_with_benchmark'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/actionpack-1.13.6/lib/action_controller/rescue.rb:83:in `measure'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/actionpack-1.13.6/lib/action_controller/benchmarking.rb:66:in `perform_action_with_benchmark'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/actionpack-1.13.6/lib/action_controller/rescue.rb:83:in `perform_action_with_rescue'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/actionpack-1.13.6/lib/action_controller/base.rb:435:in `send'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/actionpack-1.13.6/lib/action_controller/base.rb:435:in `process'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/actionpack-1.13.6/lib/action_controller/filters.rb:684:in `process_with_filters'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/actionpack-1.13.6/lib/action_controller/session_management.rb:114:in `process_with_session_management_support'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/actionpack-1.13.6/lib/action_controller/base.rb:334:in `process'
    /software/sonar-1.2/lib/sonar-web/WEB-INF/gems/gems/rails-1.2.6/lib/dispatcher.rb:41:in `dispatch'