Log Rescue is free and unsupported and there has been no development work done on this product for quite a while.
While it should fully support SQL 2000 it does not support SQL 2005 or 2008, so if any of your sources are SQL 2005 or SQL 2008 it will not work.
Also as there is no work being done on it any changes to other products won't be catered for in Log Rescue.
If it is telling you that the backup file format is unsupported then I'm afraid that there is not much that I can do. I'm sorry that I can't be of more help.
The forum might offer more insight - http://www.red-gate.com/MessageBoard/viewforum.php?f=21
I'm sorry that I can't be more help.