Redmine

Hi,

I use Redmine 2.4.1 and it stop send email when update issues.

However, Redmine 2.4.1 also send email successfully when I update Wiki and Forum.

Please help me!

Environment:
Redmine version 2.4.1.stable
Ruby version 1.9.3-p448 (2013-06-27) [x86_64-linux]
Rails version 3.2.15
Environment production
Database adapter Mysql2
SCM:
Subversion 1.6.11
Mercurial 1.4
Bazaar 2.1.1
Git 1.7.1
Redmine plugins:
advanced_membership_management 0.0.1
project_section 0.0.1b
projects_tree_view 0.0.7
redmine_add_subversion_links 0.2.0
redmine_anonymous_authors 0.0.4
redmine_checkout 0.6-BETA
redmine_code_review 0.6.1
redmine_contacts 3.2.4-light
redmine_contacts_invoices 2.2.1-light
redmine_embedded_video 0.0.3.1
redmine_evm 0.9.1
redmine_knowledgebase 2.2.0
redmine_lightbox 0.0.1
redmine_scm 0.4.3
redmine_theme_changer 0.1.1
redmine_user_profiles 0.1.1
redmine_wiki_extensions 0.6.4
redmine_wiki_gchart_formula 0.0.5
reklama 0.2.0
scrum2b 0.1
wiking 0.0.4