I'm trying to add a probe, by probe number, to an existing, running measurement, using curl, following the example and description on page 84 of the "RIPE Atlas API v2 manual". However, I'm getting an error message that does not clearly point me to the problem, and thus allow me to correct my error. Here's what I'm entering (with the <.> as placeholders, explained below) curl -H "Content-Type: application/json" -H "Accept: application/json" -X POST -d '{"probes":[{"action":"add","requested":1,"type":"probes","value":"<p>"}]}' https://atlas.ripe.net/api/v2/measurements/<m>/participation-requests/?key=<; a> where: <p> is the number of the probe I'm trying to add, and I can access it at https://atlas.ripe.net/probes/<p> <m> is the measurement to which I'm trying to add it - it's a running measurement, and I can access it at https://atlas.ripe.net/measurements/<m> <a> is the API key, which is enabled and has "Update an existing measurement" granted The error I get back is: {"error":{"status":400,"code":104,"detail":"JSON parse error - No JSON object could be decoded","title":"Bad Request"}} In case it's relevant, I'm running curl 7.53.1 on Windows 10. Thanks in advance for any suggestions. colin