How to validate field with brackets in name

Hi,

i have 3 radio buttons with the following name:

radio name="button[10]" value="15"
radio name="button[10]" value="16"
radio name="button[10]" value="17"

This is the rule:

PHP Code:

$rules = [
  'button[10]' => [
    'label' => '',
    'rules' => 'required',
    'errors' => [
      'required' => 'Please check the radio button'
    ]
  ]
]; 


If i check one radiobutton the error message is still displayed. what i am doing wrong?