If you are using pdf-writer with login engine, you can encounter a nasty problem with transactions in login engine like me(gosh… this was crazy). This is because login engine uses transaction-simple module (which is a part of transaction-simple by Austin Ziegler but not the whole gem) included in rails 1.1 in active record.
While including pdf-writer it require the whole transaction-simple library.So in such a case the simple.rb file is required twice in the application.Which creates a problem in registration in login engine as it uses tranactions.
This ticket is discussed in here and a patch is also available…
Bad news is it can not be fixed before rails version 2 according to DHH ‘s response[:(]