I find that sometimes, the value = "" is missing. So I am reverting to querying for the normalized inner Text.
<label><input type="radio" name="addThree">A Radio</label>
<label><input type="checkbox" name="hasPic"> A Checkbox </label>
Here are the xpath's respectively...Are these correct?
//label/input[normalize-space(text()) = "A Radio"]
//label/input[normalize-space(text()) = "A Checkbox"]