POSTing FormData via REST API v2.0

Hi there,

I am trying to post data to an Eloqua Form via the REST API v2.0

I am using a library called Elomentary: https://github.com/tableau-mkt/elomentary

I make the call and am getting an error with HTTP Code 501: We're sorry, but this asset can't be opened, as it uses features not supported in E10.

Any insights as to what could cause this?

The request:

POST https://secure.eloqua.com/API/REST/2.0/data/form/19

{"type":"FormData","fieldValues":[{"id":"260","value":1}, ... TRUNCATED ... ]}

Thanks!