not able to download attachment frm AP supplier invoice

Content

We have added files through front end (Fusion ERP) of different attachments for particular supplier invoice. How ever, when we try to get them REST / SOAP ui, not able to retrieve them

 

https://xyx/fscmRestApi/resources/11.13.18.05/invoices/XAP01/child/attachments  (as a REST API)

also

through ErpObjectAttachmentService like

<typ:downloadAttachment>
         <typ:attachment>
             <ns1:EntityName>AP_INVOICES_ALL</ns1:EntityName>
            <ns1:CategoryName>AP_SUPPORTING_DOC</ns1:CategoryName>
            <ns1:UserKeyA>NR SE</ns1:UserKeyA>
            <ns1:UserKeyB>XAP01</ns1:UserKeyB>
            <ns1:UserKeyC>10001</ns1:UserKeyC>
            <ns1:UserKeyD>#NULL</ns1:UserKeyD>
            <ns1:UserKeyE>#NULL</ns1:UserKeyE>
         </typ:attachment>
      </typ:downloadAttachment>

 

It says There are no attachments present for provided user keys