The default notification scheme for JIRA has changed. You will no longer get a notification when an issue is created. You will still get emails when an issue is assigned to you, you created an issue, or if you watch an issue.
Instead you should use the ability to create a filter and subscribe to any changes to this filter. For a good description on how to use this see http://blogs.atlassian.com/2013/05/bulk-watch-meet-the-new-jira/. I for example have created a filter for a project that will send me an email when anything happens for that particular project. I selected the advanced option that will send me an update of any changes every 15 minutes (using the following 0 0/15 * * * ? * for the advanced option).