Import AP Invoice from own excel file failed

Hi all.

I create my own excel file with the same sheet name, column name as exported one. however, it failed to import with the error below.

However, copy pasting the content to an exported excel file seems to works fine. 

The issue is: I am going to do a data conversion program from raw file to a generated excel file with sage template to import data.

I cannot ask user to copy paste the content to exported excel file from sage 300 every time they do data conversion.

what makes the excel generated from sage different from a normal excel file that we create our own?

Thank you.