the __YEAR__ is just an example for a substitution variable, so the code won’t help me.
I THINK the problem is not to load the extra field itsself, the problem is that on the line level the substitution variable’s content is not loaded within the extra field.
Doing the same on the invoice header works as expected (also with the substitution variable __YEAR__ behind it). This screenshot shows the web interface:
this one the result on the PDF (template sponge):
