Looking at the code you have pasted there seems to be few issues with it.
- a new Validator instance is created on every button click
- also a separate Validator is attached to every radio button element
The best approach will be to attach the Validator to the list instead to the individual radio buttons and to change the click event handler to get reference to the widget and to call its validate method.
In order message placeholder to be picked-up it should be located within the container to which the Validator is attached. This is not possible in your scenario as the placeholder is outside of the container. In order this to work you could implement a custom message locator in order to supply the correct container.
you can find a test page which demonstrate the suggested changes.
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