Hi Carole,
Why do you want to do so. I would suggest you to check the data in order_save badi rather than trying to play with transaction_context. In order_save badi you can check for the object type and decide for youself wheather you want to save the record or not.
If you do not want to save raise the exception "DO_NOT_SAVE".
In Case, if you still want to use transaction_context. Please share us the component and view details, we will check and try to help you.
Regards,
Jotsaroop Singh