Date/time picker in prompter dialog

Hi,

i’m using the prompter dialog to enter text and date/time for a new cild record:

…

let prompter = Prompter.new();
prompter.addParameter(‘Note:’, ‘note’, ‘text’)
.addParameter(‘DateTime:’, ‘datetime’, ‘date_time’)
.show(‘Message prompt’, callbackFunction);

The field “Note” is filled with the texted i entered in the dialog, but “DateTime” is still empty. What is wrong with my script?

Is it possible to add days/weeks/years (choosing from picklist in the prompter dialog) to the current date and add the result in the DateTime field in the created record?

Thanks
Chris