Telegram Plugin doesn't works

Hello!!
Recently I’ve install Graylog 3.1 and this Telegram Plugin (https://marketplace.graylog.org/addons/8a67cfdf-8c1c-4d17-87bf-db38e79015f1).

The plugin starts with graylog, and I can configure the notification, but when I try to send a message, I receive this message:

``` Caused by: org.graylog.events.notifications.PermanentEventNotificationException: Couldn't send legacy notification - legacy notifications cannot be retried!
at org.graylog.events.legacy.LegacyAlarmCallbackEventNotification.execute(LegacyAlarmCallbackEventNotification.java:67) ~[graylog.jar:?]


at org.graylog.events.notifications.EventNotificationExecutionJob.execute(EventNotificationExecutionJob.java:135) ~[graylog.jar:?]


… 11 more

Caused by: java.lang.NullPointerException

at de.sandstorm_projects.telegramAlert.TelegramBot.sendMessage(TelegramBot.java:43) ~[?:?]


at de.sandstorm_projects.telegramAlert.TelegramAlarmCallback.call(TelegramAlarmCallback.java:47) ~[?:?]


at org.graylog.events.legacy.LegacyAlarmCallbackSender.send(LegacyAlarmCallbackSender.java:87) ~[graylog.jar:?]


at org.graylog.events.legacy.LegacyAlarmCallbackEventNotification.execute(LegacyAlarmCallbackEventNotification.java:64) ~[graylog.jar:?]


at org.graylog.events.notifications.EventNotificationExecutionJob.execute(EventNotificationExecutionJob.java:135) ~[graylog.jar:?]


… 11 more`

Any Ideas?

the Plugin creator might need to adjust that plugin for the Graylog Version.