i have the same problem:
i am running Alfresco 2.1 on my server and OO is running in headless mode (listening on port 8100)!!!!
i tried to transform plain text into a pdf, but i get the following error:
Failed to run Actions due to error: No transformation exists between mimetypes text/plain and application/pdf
i tried to transform a pdf into plain text and it worked! but the other way round i always get the error (same problem when i try to convert a word file into pdf)
hope someone can help, thx!