Set Dynamic Image URL in Nintex Form

In Nintex Form, I have a calculated value which value is set though Lookup function.

The calculated Value contains URL of an image.

How can I set this URL to be the image URL of an image control.

I did the following..

CSS class of calculated value = photoLink

CSS class of Image control = personalPhoto

In Java script of the form, I defined the following but no thing is happening .. any suggestions?:

NWF$(".photoLink").change(function(){
setLink();
});
function setLink() {

var linkValue = NWF$(".photoLink").val();

NWF$('.personalPhoto').attr('href',linkValue);

}