Have a look at the log files located in the FlyFF Transformation directory.
Did it inject successfully?
On many private servers you need to adjust startup argument (sunkist on official), or for the second method, you need to change "FlyFF patcher window name=FLYFF" in the FlyFF Transformation.ini file, also located in the FlyFF Transformation directory. You can find the patcher window name by opening the patcher and using the Task-Manager.
Did it inject successfully?
On many private servers you need to adjust startup argument (sunkist on official), or for the second method, you need to change "FlyFF patcher window name=FLYFF" in the FlyFF Transformation.ini file, also located in the FlyFF Transformation directory. You can find the patcher window name by opening the patcher and using the Task-Manager.