Importing Invoices

I have tried to import our invoices by downloading the sample sheet that shows you which data you have to fill in order to import the invoices, however, everytime I tried to upload the excel sheet a message appears that says "the given data was invalid" even though I wrote everything that's supossed to be written and I can't figure out where the problem is. Can someone help?

same issue.. even when I try to upload the "sample" which is directly downloaded from that tab...