Incompatibility with Luxury Buttons plugin

[fghd]

The plugin has an incompatibility with Luxury Buttons plugin. Tasks are not creating, but time when tasks will be created is increased. I've found the following error in code:

irb(main):002:0> issue = Issue.new(:project_id=>122, :tracker_id=>5, :category_id=>nil, :assigned_to_id=>6, :author_id=>19, :subject=>"ttt", :description=>"ttt");
irb(main):003:0* issue.save!
ActiveRecord::RecordInvalid: Validation failed: You couldnt save issues with this tracker from /usr/local/bundle/gems/activerecord-4.2.6/lib/active_record/validations.rb:79:in raise_record_invalid'
from /usr/local/bundle/gems/activerecord-4.2.6/lib/active_record/validations.rb:43:in save!' from /usr/local/bundle/gems/activerecord-4.2.6/lib/active_record/attribute_methods/dirty.rb:29:in save!'
from /usr/local/bundle/gems/activerecord-4.2.6/lib/active_record/transactions.rb:291:in block in save!' from /usr/local/bundle/gems/activerecord-4.2.6/lib/active_record/transactions.rb:351:in block in with_transaction_returning_status'
from /usr/local/bundle/gems/activerecord-4.2.6/lib/active_record/connection_adapters/abstract/database_statements.rb:213:in block in transaction' from /usr/local/bundle/gems/activerecord-4.2.6/lib/active_record/connection_adapters/abstract/transaction.rb:184:in within_new_transaction'
from /usr/local/bundle/gems/activerecord-4.2.6/lib/active_record/connection_adapters/abstract/database_statements.rb:213:in transaction' from /usr/local/bundle/gems/activerecord-4.2.6/lib/active_record/transactions.rb:220:in transaction'
from /usr/local/bundle/gems/activerecord-4.2.6/lib/active_record/transactions.rb:348:in with_transaction_returning_status' from /usr/local/bundle/gems/activerecord-4.2.6/lib/active_record/transactions.rb:291:in save!'
from (irb):3
from /usr/local/bundle/gems/railties-4.2.6/lib/rails/commands/console.rb:110:in start' from /usr/local/bundle/gems/railties-4.2.6/lib/rails/commands/console.rb:9:in start'
from /usr/local/bundle/gems/railties-4.2.6/lib/rails/commands/commands_tasks.rb:68:in console' from /usr/local/bundle/gems/railties-4.2.6/lib/rails/commands/commands_tasks.rb:39:in run_command!'
from /usr/local/bundle/gems/railties-4.2.6/lib/rails/commands.rb:17:in <top (required)>' from bin/rails:4:in require'
from bin/rails:4:in `

'

How can I solve the problem?