Went round and round with this today. Creating a rule to upload image files to my hosting server, tested with several ftp clients then remembered we have the ability to monitor the directory in Hazel and not worry about scheduling.
;TLDR - I created a login using Transmit which of course was placed in Keychain. Hazel Fails. Delete the Transmit entry and create the Rule in Hazel, have it connect to the FTP Server and hit the OPEN button which then saves the login information in Keychain.
Until I deleted the Transmit Keychain entry Hazel refused to create the rule, it would connect to the FTP server but fail when trying to finish setting up the rule. I kept getting "Could not save to keychain" errors.