Validation error in form using "steps" function

Hi. i have a form using the new steps function (Layout->Pages(New)

i have set 3 steps in total.

in step 1 there is a varchar field called “cN” that when is set with value cN+ does not allow me to proceed to step 2 of the filling process.
any other value for the filed is ok.
if i try to proceed to the next step an error appears me telling that the data is not valid (should not it be since it is a varchar?)
i guess there is some validating process going on when you use the steps function.
Any suggestion?
Thanks

Immagine 2022-04-04 101143