I have never worked with TLB, but as a guess...
Does method LInvoice.Edit ( or similar ) exist? What if You try to use LInvoice.Edit () instead of LInvoice.New?
Head office is in Israel (if i understand correctly). And its a possible that the language of communication will be english (but a russian accent is possible too ) :
https://www.mekashron.com/blog/ru/
PaPaNi replied to Tommi Prami's topic in General Help
Top 3 for me, where i make the most mistakes, are words: Height, Length and Exception (even now I should check these words 😀) => i try to avoid using Exceptions (joke).