Difficulty creating a data pipeline with Fabric Datafactory using REST

I am creating a data pipeline in Fabric Data Factory using date as a parameter. However, the system presents the following error:enter image description here

And I wanted to pass a date in variable format that always collects the current day and sets it in the variable {vi}, and the day following {vi} in {vf}.

However, I can't get the system to work even by passing the dates in a fixed way as shown in the example below:

enter image description here

However, I get this error:

enter image description here

Does anyone have any ideas on how I should proceed in this case?