setting a different src picture in a webpage with javascript

Question

I'm trying to change a picture in a webpage using the tag button and the onclick attribute that call a function that I did in a js document, but it isn't working, this is what a did:

in Javascript:

function store (a,z) {
  var pic;
  if (a>z) {
       pic = "images_weddings/desing_logo-01.jpg";
  }else{
       pic = "images_weddings/rose1.jpg";
  }
  document.getElementById('change1').src = pic;
}

and in html:

MATRIMONIOS

  <div>
      <img src="images_weddings/desing_logo-01.png" id="change1" >
  </div>

  <button type="button" onclick="store(2,3)">change the image</button>