Quick price changer

Hi all, can anyone help me with the quick price change app?
The app displays the error message „Net list price 0“ for many variants in the preview and consequently does not update the prices. However, I have provided both the net and gross prices for both the parent article and the variants. What does the app mean by net list price, and how can I efficiently transfer it to all articles and variants as quickly as possible?
Thanks in advance
Greta