hi ,
it s normal to have your xml file in the same line like this :
<?xml version="1.0" encoding="UTF-8"?>
<tns:Invoicing xmlns:tns="xxxxxxx"><tns:FileNumber>20180919093512</tns:FileNumber><tns:FileDate>2018-09-19</tns:FileDate></tns:Invoicing>
because i alwayse have an error when i upload this file like that otherwise when i formt it to be like that :
<?xml version="1.0" encoding="UTF-8"?>
<tns:Invoicing xmlns:tns="xxxxxxx">
<tns:FileNumber>20180919093512</tns:FileNumber>
<tns:FileDate>2018-09-19</tns:FileDate>
</tns:Invoicing>