You do not have permissions to add messages for the task or change the task handler.
Click the Current User -> Statuses... menu item.
Select the status and check permissions.
There are no message types available that move the task to the desired target state, or you do not have permissions to add messages of the required type. To check available message types and message type permissions:
Click the Current task -> Workflow... menu item.
Click the task's workflow.
Click the Message Types tab.
Click the message type for which you want to view permissions.
Click the Permissions tab.
There are no available handlers for this task. To see the available handlers click the Current Task -> Access Control Rules... menu item.