XML GATEWAY Issue

Hi,

We are importing AP invoices via XML Gateway.  This is working fine in general but we are facing an issue with extended fields under the USERAREA tag.  We have created the extension definition and uploaded it succesfully.  However when it comes to mapping the new element the value is ignored

This is the relevent part of the XML call

<PROCESS_INVOICE>

         <INVHEADER>

            <AMOUNT qualifier="DOCUMENT" type="T" index="1">

               <VALUE>t</VALUE>

               <NUMOFDEC>2</NUMOFDEC>

               <SIGN>+</SIGN>

               <CURRENCY>EUR</CURRENCY>

               <DRCR>D</DRCR>

            </AMOUNT>

            <DATETIME qualifier="DOCUMENT">

               <YEAR>2019</YEAR>

               <MONTH>02</MONTH>

               <DAY>17</DAY>

               <HOUR>12</HOUR>

               <MINUTE>00</MINUTE>

               <SECOND>00</SECOND>

               <SUBSECOND>0</SUBSECOND>