Postman - Append file(s) to a Data Record collection doesn't work

I'm using Postman on my windows laptop and added a pdf document as value (called factuur.pdf). 

In DocuWare I created a data record (DocID #1) and reffering to the record in Postman. 

When I run the collection I get a 200OK but my document isn't added in DocuWare.

Please See attached screenshots

 

I added also the DW screenshot