Gernot,
Send me an email it's just my [Removed by Moderator] and I will send you the updated version of the actions.
The reason why this version of the JTA actions breaks is due to a change in the interface to the Security API for retrieving the credentials from the credential store of MII. There are other minor changes and adjustments to the updated version and I should point out that this functionality has been rolled into standard product as of the MII 14.0 release.
Sam