zBooks Custom Script with deluge - Custom Field shows NULL

zBooks Custom Script with deluge - Custom Field shows NULL

I am trying to read a custom-field from the item module, which is a decimal.

time = item.get("cf_reparatur_dauer_h");

The answer is always NULL.

I have already seen similar topics in the forum, but they are already 4 years old and do not work (anymore).

Thank you very much for your help.