When I try to use the Jira reporter plug-in to connect our Jenkins instance with an (Atlassian-hosted) Jira instance, it fails to work. When I check the debug output, I have:

17:54:23 Build step 'Publish JUnit test result report' changed build result to UNSTABLE
17:54:25 [JiraTestResultReporter] [INFO] Examining test results...
17:54:25 [JiraTestResultReporter] [DEBUG] Build result is UNSTABLE
17:54:25
17:54:25 [JiraTestResultReporter] [DEBUG] [JiraTestResultReporter] [INFO] Workspace is /home/jenkins/webapps/syapse/src/syapse
17:54:25
17:54:29 [JiraTestResultReporter] [DEBUG] projectKey: AP
17:54:29 [JiraTestResultReporter] [DEBUG] errorDetails: expected false to equal true
17:54:29 [JiraTestResultReporter] [DEBUG] fullName: AccountCredentialsContentView FAKE! (do not panic).please ignore: Jeremy W. is testing the Jira-Jenkins plug-in
17:54:29 [JiraTestResultReporter] [DEBUG] simpleName: AccountCredentialsContentView FAKE! (do not panic)
17:54:29 [JiraTestResultReporter] [DEBUG] title: Case Result: please ignore: Jeremy W. is testing the Jira-Jenkins plug-in
17:54:29 [JiraTestResultReporter] [DEBUG] packageName: (root)
17:54:29 [JiraTestResultReporter] [DEBUG] name: please ignore: Jeremy W. is testing the Jira-Jenkins plug-in
17:54:29 [JiraTestResultReporter] [DEBUG] className: AccountCredentialsContentView FAKE! (do not panic)
17:54:29 [JiraTestResultReporter] [DEBUG] failedSince: 1470
17:54:29 [JiraTestResultReporter] [DEBUG] status: FAILED
17:54:29 [JiraTestResultReporter] [DEBUG] age: 1
17:54:29 [JiraTestResultReporter] [DEBUG] ErrorStackTrace: Error: expected false to equal true
17:54:29 at file:///home/jenkins/webapps/syapse/src/syapse/static/js/test/expectjQueryAssertions.js?v=undefined:96
17:54:29 at file:///home/jenkins/webapps/syapse/src/syapse/static/js/ext/expect.js:203
17:54:29 at file:///home/jenkins/webapps/syapse/src/syapse/static/js/ext/expect.js:73
17:54:29 at file:///home/jenkins/webapps/syapse/src/syapse/static/js/test/mocha/account/views/AccountCredentialsContentViewTests.js?v=undefined:20
17:54:29 at file:///home/jenkins/webapps/syapse/src/syapse/static/js/ext/mocha/mocha.js:4106
17:54:29 at file:///home/jenkins/webapps/syapse/src/syapse/static/js/ext/mocha/mocha.js:4475
17:54:29 at file:///home/jenkins/webapps/syapse/src/syapse/static/js/ext/mocha/mocha.js:4534
17:54:29 at next (file:///home/jenkins/webapps/syapse/src/syapse/static/js/ext/mocha/mocha.js:4401)
17:54:29 at file:///home/jenkins/webapps/syapse/src/syapse/static/js/ext/mocha/mocha.js:4410
17:54:29 at next (file:///home/jenkins/webapps/syapse/src/syapse/static/js/ext/mocha/mocha.js:4354)
17:54:29 at file:///home/jenkins/webapps/syapse/src/syapse/static/js/ext/mocha/mocha.js:4378
17:54:29 at timeslice (file:///home/jenkins/webapps/syapse/src/syapse/static/js/ext/mocha/mocha.js:5361)
17:54:29 [JiraTestResultReporter] [DEBUG] affectedFile: Error: expected false to equal true
17:54:29 at file:///static/js/test/expectjQueryAssertions.js?v=undefined:96
17:54:29 at file:///static/js/ext/expect.js:203
17:54:29 at file:///static/js/ext/expect.js:73
17:54:29 at file:///static/js/test/mocha/account/views/AccountCredentialsContentViewTests.js?v=undefined:20
17:54:29 at file:///static/js/ext/mocha/mocha.js:4106
17:54:29 at file:///static/js/ext/mocha/mocha.js:4475
17:54:29 at file:///static/js/ext/mocha/mocha.js:4534
17:54:29 at next (file:///static/js/ext/mocha/mocha.js:4401)
17:54:29 at file:///static/js/ext/mocha/mocha.js:4410
17:54:29 at next (file:///static/js/ext/mocha/mocha.js:4354)
17:54:29 at file:///static/js/ext/mocha/mocha.js:4378
17:54:29 at timeslice (file:///static/js/ext/mocha/mocha.js:5361)
17:54:29 [JiraTestResultReporter] [DEBUG] ----------------------------
17:54:29 [JiraTestResultReporter] [DEBUG] Creating issue in project AP at URL https://syapse.atlassian.net/rest/api/2/issue/
17:54:29
17:54:29 [JiraTestResultReporter] [INFO] Reporting issue.
17:54:30 [JiraTestResultReporter] [DEBUG] statusLine: HTTP/1.1 400 Bad Request
17:54:30
17:54:30 [JiraTestResultReporter] [DEBUG] statusCode: 400
17:54:30
17:54:30 ERROR: Publisher JiraTestResultReporter.JiraReporter aborted due to exception
17:54:30 java.lang.RuntimeException: [JiraTestResultReporter] [ERROR] Failed : HTTP error code : 400
17:54:30 at JiraTestResultReporter.JiraReporter.createJiraIssue(JiraReporter.java:188)
17:54:30 at JiraTestResultReporter.JiraReporter.perform(JiraReporter.java:108)
17:54:30 at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
17:54:30 at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:745)
17:54:30 at hudson.model.AbstractBuild$AbstractBuildExecution.performAllBuildSteps(AbstractBuild.java:709)
17:54:30 at hudson.model.Build$BuildExecution.post2(Build.java:182)
17:54:30 at hudson.model.AbstractBuild$AbstractBuildExecution.post(AbstractBuild.java:658)
17:54:30 at hudson.model.Run.execute(Run.java:1734)
17:54:30 at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
17:54:30 at hudson.model.ResourceController.execute(ResourceController.java:88)
17:54:30 at hudson.model.Executor.run(Executor.java:231)
17:54:32 Finished: FAILURE

Any help would be appreciated.