Checkbox Group Required Field

[Grischabock]

Hello everyone

I have created a form in which the user has to choose from one of three options with one option (radio). I have put each element in the same group, so I have deposited a label then a group name and a value. But now I have not found a way as I can say that from the group XY at least one field must be checked.

What did I miss or is it really not possible?

Thank you for inputs

[Norm]

Could you please share a screen shot of your form?

[Grischabock]

I have attached an excerpt from the form as well as the setting. At the bottom I have two more checkboxes where I have the same problem, the user must select one of the two.