Libary Sync with Flow

Hello to all,

i have creat two libarys in SharePoint. In the First Libary we columne with a calculated value generated.

Formel: =RECHTS(LINKS(Betreff;SUCHEN(";REDAT;";Betreff;1)-3);LÄNGE(LINKS(Betreff;SUCHEN(";REDAT;";Betreff;1)-10))-SUCHEN(";DokNr;";LINKS(Betreff;SUCHEN(";REDAT;";Betreff;1)-1);1))

The Column attitude is: value Calculate, Date

This Value i would like to send with Flow in the second Libary.
The Column attitute is: Date

The Flow send error message:

OpenApiOperationParameterTypeConversionFailed. The 'inputs.parameters' of workflow operation 'Dateieigenschaften_aktualisieren' of type 'OpenApiConnection' is not valid. Error details: Input parameter 'item/Belegdatum' is required to be of type 'String/date'. The runtime value '"20.06.2019"' to be converted doesn't have the expected format 'String/date'.

I can not Change the column attitut in the Libarys. How can solved this problem?

Thanks for your Help