Smappee Charger Postman

Hello, I try to give a Smappee charger a limit of 10 amps while charging. This with a URL.
I have the correct acces_token and for the Serialnumber I used the deviceSerialNumber. The charger has 1 connector so for position I used 1.

When I sent the URL I get an error.
See link for more details: Set the charging mode of one of the connectors of a charging station - Smappee API - Confluence (atlassian.net)

Any tips?
Thanks

The serialnumber of the device wasn’t the same as in the Smappee App, when I used the number of the app it worked!