I'm trying to use CKFinder 3 in a very simple form like the one below, but when pressing "Browse server" button(s), the CKFinder appears briefly, then the page gets redirected to "save.php" like the submit button was clicked. If I remove <form> and </form> tags, CKFinder opens normally, but I can't submit the form. What I'm missing here? Thanks!

...
<form action="save.php" method="post" >
   <input id="ckfinder-input-1" type="text" >
   <button id="ckfinder-modal-1">Browse Server</button>
      <div style="height: 5px"></div>
   <input id="ckfinder-input-2" type="text" >
   <button id="ckfinder-modal-2">Browse Server</button>
      <div style="height: 5px"></div>
   <button type="submit">Save</button>
</form>
...
<script src="ckfinder/samples/js/sf.js"></script>
<script src="ckfinder/samples/js/tree-a.js"></script>
<script src="ckfinder/ckfinder.js"></script>
<script>

    var button1 = document.getElementById( 'ckfinder-modal-1' );
    var button2 = document.getElementById( 'ckfinder-modal-2' );

    button1.onclick = function() {
        selectFileWithCKFinder( 'ckfinder-input-1' );
    };
    button2.onclick = function() {
        selectFileWithCKFinder( 'ckfinder-input-2' );
    };

    function selectFileWithCKFinder( elementId ) {
        CKFinder.modal( {
            chooseFiles: true,
            width: 800,
            height: 600,
            onInit: function( finder ) {
                finder.on( 'files:choose', function( evt ) {
                    var file = evt.data.files.first();
                    var output = document.getElementById( elementId );
                    output.value = file.getUrl();
                } );

                finder.on( 'file:choose:resizedImage', function( evt ) {
                    var output = document.getElementById( elementId );
                    output.value = evt.data.resizedUrl;
                } );
            }
        } );
    }
</script>