Hi Christophe
Where did you find this coding example?
Although I am not familiar with your programming example, I expect that it should also work in the context of a BW Transformation.
However, let's check it. I suggest to make a small custom program using t/code SE38 and test the coding here. I use this approach regularly to be sure that my syntax is correct and it's very easy to debug it from here.
Please share your findings. Thanks in advance.
Best regards,
Sander