Redmine

I new for the redmine and I create the new issue but I found the problem when I try to fill in field "spent time" I found the error page in the attach file "BIB-031.png" that I checking the log file
But I don't know what is cause of error Please help me ,What I have to do for fix or patch this error ?

Processing IssuesController#update (for 172.17.2.188 at 2011-03-03 16:17:01) [PUT]
Parameters: {"time_entry"=>{"billed_hours"=>"", "comments"=>"", "end_minute"=>"0", "activity_id"=>"9", "start_hour"=>"9", "start_minute"=>"0", "hours"=>"8.00", "end_hour"=>"17"}, "commit"=>"Submit", "notes"=>"", "action"=>"update", "_method"=>"put", "authenticity_token"=>"1XExCMGyc330cAeWvNFE2B1THTivYY96wzUEUUlKVSo=", "id"=>"33", "issue"=>{"start_date"=>"2011-03-02", "estimated_hours"=>"4", "priority_id"=>"5", "parent_issue_id"=>"", "lock_version"=>"4", "assigned_to_id"=>"4", "subject"=>"Modify Document for install new CR", "tracker_id"=>"1", "due_date"=>"2011-03-02", "status_id"=>"5", "description"=>"Modify Document for install new CR."}, "controller"=>"issues", "attachments"=>{"1"=>{"description"=>""}}}

NoMethodError (super: no superclass method `spent_on=' for #<TimeEntry:0xb5ff6cb0>):
app/models/time_entry.rb:68:in `spent_on='
app/models/issue.rb:542:in `save_issue_with_child_records'
app/models/issue.rb:536:in `save_issue_with_child_records'
app/controllers/issues_controller.rb:169:in `update'

Rendering /opt/redmine-1.1.0-0/apps/redmine/public/500.html (500 Internal Server Error)