Getting 422 when trying to supply client_order_id

Alpaca Integration Applications
1

I am trying to post the following JSON

{“symbol”: “LUNR”, “qty”: “2042”, “side”: “buy”, “type”: “limit”, “limit_price”: “12.24”, “time_in_force”: “ioc”, “client_order_id”: “35899”}

…and getting 422 Unprocessable entity.

How do I supply client_order_id param? It works if I do not use client_order_id.