How to set smartsheet checkbox from appsheet?

Hi all,
I like using appsheet with smartsheet and have a question, how to set a smartsheet checkbox from appsheet?

Appsheet shows the column “bearbeitet” as YES/NO but if I change the value I get this message:

Unable to add/edit/delete row in table ‘gefährliche Situationen Workflow’. → Der Wert “true” konnte nicht in der Spalte “bearbeitet” gespeichert werden. Diese Spalte ist nur auf Werte vom Typ "CHECKBOX begrenzt. → Error updating cell(s) in Smartsheet

Google translator:

Unable to add / edit / delete row in table ‘dangerous workflow situations’. → The value “true” could not be saved in the “edited” column. This column is only limited to values of the type "CHECKBOX. → Error updating cell (s) in Smartsheet

Any idea how to fix this?

Thank you very much