radio input fields are composed by items.
Each one of this items must have a label and a value. You insert this data during the creation of this items in the backend.
Than you apply conditions in base of which the images should change.
This conditions must be created in base of the values that this items holds, not labels.
That is the first thing you should check.
Another thing if to be sure that the conditions are inserted correctly.
Try this steps, if you have problems again please send us an email describing in details the problem and when it happens.
Would be great if you have a development environment we can check the error and solve it or some WordPress credentials of the current environment.