Error saving milestone

[SergeST]

hi, when trying to save milestones an exception is thrown.
couldnt find how to solve it

DEBUG: Unable to import tasks:
C:/sergio/redmine/redmine-1.0.0/vendor/rails/activerecord/lib/active_record/validations.rb:1090:in save_without_dirty!' C:/sergio/redmine/redmine-1.0.0/vendor/rails/activerecord/lib/active_record/dirty.rb:87:insave_without_transactions!'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/activerecord/lib/active_record/transactions.rb:200:in save!' C:/sergio/redmine/redmine-1.0.0/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:136:intransaction'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/activerecord/lib/active_record/transactions.rb:182:in transaction' C:/sergio/redmine/redmine-1.0.0/vendor/rails/activerecord/lib/active_record/transactions.rb:200:insave!'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/activerecord/lib/active_record/transactions.rb:208:in rollback_active_record_state!' C:/sergio/redmine/redmine-1.0.0/vendor/rails/activerecord/lib/active_record/transactions.rb:200:insave!'
C:/sergio/redmine/redmine-1.0.0/vendor/plugins/redmine_loader/app/controllers/loader_controller.rb:256:in create' C:/sergio/redmine/redmine-1.0.0/vendor/plugins/redmine_loader/app/controllers/loader_controller.rb:199:ineach'
C:/sergio/redmine/redmine-1.0.0/vendor/plugins/redmine_loader/app/controllers/loader_controller.rb:199:in create' C:/sergio/redmine/redmine-1.0.0/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:136:intransaction'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/activerecord/lib/active_record/transactions.rb:182:in transaction' C:/sergio/redmine/redmine-1.0.0/vendor/plugins/redmine_loader/app/controllers/loader_controller.rb:198:increate'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/base.rb:1331:in send' C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/base.rb:1331:inperform_action_without_filters'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/filters.rb:617:in call_filters' C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/filters.rb:610:inperform_action_without_benchmark'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/benchmarking.rb:68:in perform_action_without_rescue' C:/sergio/redmine/redmine-1.0.0/vendor/rails/activesupport/lib/active_support/core_ext/benchmark.rb:17:inms'
C:/Ruby187/lib/ruby/1.8/benchmark.rb:308:in realtime' C:/sergio/redmine/redmine-1.0.0/vendor/rails/activesupport/lib/active_support/core_ext/benchmark.rb:17:inms'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/benchmarking.rb:68:in perform_action_without_rescue' C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/rescue.rb:160:inperform_action_without_flash'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/flash.rb:146:in perform_action' C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/base.rb:532:insend'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/base.rb:532:in process_without_filters' C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/filters.rb:606:inprocess'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/base.rb:391:in process' C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/base.rb:386:incall'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/routing/route_set.rb:437:in call' C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/dispatcher.rb:87:indispatch'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/dispatcher.rb:121:in _call' C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/dispatcher.rb:130:inbuild_middleware_stack'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/activerecord/lib/active_record/query_cache.rb:29:in call' C:/sergio/redmine/redmine-1.0.0/vendor/rails/activerecord/lib/active_record/query_cache.rb:29:incall'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb:34:in cache' C:/sergio/redmine/redmine-1.0.0/vendor/rails/activerecord/lib/active_record/query_cache.rb:9:incache'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/activerecord/lib/active_record/query_cache.rb:28:in call' C:/sergio/redmine/redmine-1.0.0/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:361:incall'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/string_coercion.rb:25:in call' C:/Ruby187/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/head.rb:9:incall'
C:/Ruby187/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/methodoverride.rb:24:in call' C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/params_parser.rb:15:incall'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/session/cookie_store.rb:93:in call' C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/failsafe.rb:26:incall'
C:/Ruby187/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/lock.rb:11:in call' C:/Ruby187/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/lock.rb:11:insynchronize'
C:/Ruby187/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/lock.rb:11:in call' C:/sergio/redmine/redmine-1.0.0/vendor/rails/actionpack/lib/action_controller/dispatcher.rb:106:incall'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/railties/lib/rails/rack/static.rb:31:in call' C:/Ruby187/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/urlmap.rb:46:incall'
C:/Ruby187/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/urlmap.rb:40:in each' C:/Ruby187/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/urlmap.rb:40:incall'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/railties/lib/rails/rack/log_tailer.rb:17:in call' C:/Ruby187/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/content_length.rb:13:incall'
C:/Ruby187/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/handler/webrick.rb:50:in service' C:/Ruby187/lib/ruby/1.8/webrick/httpserver.rb:104:inservice'
C:/Ruby187/lib/ruby/1.8/webrick/httpserver.rb:65:in run' C:/Ruby187/lib/ruby/1.8/webrick/server.rb:173:instart_thread'
C:/Ruby187/lib/ruby/1.8/webrick/server.rb:162:in start' C:/Ruby187/lib/ruby/1.8/webrick/server.rb:162:instart_thread'
C:/Ruby187/lib/ruby/1.8/webrick/server.rb:95:in start' C:/Ruby187/lib/ruby/1.8/webrick/server.rb:92:ineach'
C:/Ruby187/lib/ruby/1.8/webrick/server.rb:92:in start' C:/Ruby187/lib/ruby/1.8/webrick/server.rb:23:instart'
C:/Ruby187/lib/ruby/1.8/webrick/server.rb:82:in start' C:/Ruby187/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/handler/webrick.rb:14:inrun'
C:/sergio/redmine/redmine-1.0.0/vendor/rails/railties/lib/commands/server.rb:111
C:/Ruby187/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in gem_original_require' C:/Ruby187/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:inrequire'
C:/sergio/redmine/redmine-1.0.0/script/server:3