checkoutCreate sellingplan

Hi, i am triying to add a suscription product with a selling plan to the checkout with this mutation :

But the checkout give me this error :

I am trying to send it in the variables, but everything gives me an error like this :
Variable $input of type CheckoutCreateInput! was provided invalid value for lineItems.0.sellingPlanId (Field is not defined on CheckoutLineItemInput.

Any clues? Thanks :slightly_smiling_face: