Creating a POST request in Paymo by calling a REST service

Hello,

I've been trying to create a POST request for a time entry in Paymo by calling a REST service in Mendix through the Paymo API (https://github.com/paymoapp/api/blob/master/sections/entries.md). I'm able to create a valid POST request in Fiddler but I can't get it to work in the Modeler.

This is the input I use in Mendix for the POST request:

And this is an example of a valid POST request in Fiddler (for the example I used the same data used for testing the POST request in Mendix):

When I create the request in Fiddler I receive a '201 created' notification and when I create the request in the Modeler I receive a '400 Bad request' notification. So I assume I made a mistake in configuring the REST service call in Mendix. Does anyone know how I can solve this problem?

Thanks in advance.