Error: "The backup file is encrypted, and you have not supplied the correct decryption key for th (4223184)

Error: "The backup file is encrypted, and you have not supplied the correct decryption key for this file." when adding a Subscriber to an existing plan.   Failed to execute operation -  adding a subscriber for an existing, encrypted plan.

Steps to reproduce:
1). Machine (1):  
Create new log shipping (1 publisher and 2 new subscriber -- choose encryption backup file) Setup 5 minutes interval

Example:
Machine (1) : database test1 (publisher)
Machine (2) : database test1 (subscriber) -- read only
Machine (3) : database test1 (subscriber) -- read only

2).  Machine (2): launch LiteSpeed Log Shipping 5.0  and add the third subscriber. The error displays onscreen.

Software Defect

Fixed in version 5.0.1 of LiteSpeed.

The latest version of LiteSpeed for SQL Server can be downloaded at http://support.quest.com/support_download/Downloads.asp

WORKAROUND: Delete and recreate the Log Shipping plan.