REST endpoint filterCriterion doesn't work

Summary:

I am trying to filter a table. This table has data from an REST endpoint. I added input field, assigned it a variable. This variable is added to the filterCriterion as follows:

I want to achieve filtering through specified inputs. For example filtering on attribute "bedrag".

When I use "factuurdatumtM and factuurDatumVanaf" these dynamic Query parameters work in some form.

But the "filterBedrag and filterBetaalMethode" do not work. ( I added these myself).

I created a FilterTransforms.js file and used it as "source" for Transforms. There is a basic filter generated. Do I need to change it so that I can filter on attribute "bedrag" ?