Getting Default Values won’t work

Hi.

I want to prefill a dropdown-field with a GET-Value of the url.
I tried it with /?seminar=Sage+b7+-+Inventur
also with /?seminar=Sage%20b7%20-%20Inventur
and /?seminar=Sage b7 - Inventur
But it won’t work?

Inside the form I inserted the following field:

[select seminar default:get default:1 
"Bitte w?hlen"
"Sage b7 – Inventur"]

Could you please advise, how to get it working?
Thanks for your support!

Regards,
J?rg

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