Get duration of days (passed days)

[newapp]

Hello,
I've got a question concerning an app I'm about to programm.
You can answer me in german or english.

I want to store the startdate ("startdatum") in TinyDB - this should be done with the Datepicker1.
Then I want to load this startdate in an other place of the program to get the passed days ("vergTage").
Below you can see the error message.

Please be so kind and help me with this problem...

[dora_paz]

Try something like this

[newapp]

Hello dora_paz,
thanks a lot for your very good help!!
Now it works...
Thank you!!

[Anke]

Or this: