Changing alternative image imagemapster

Question

I was experimenting with image maps. Came across the problem: I am not able to change the image of area itself I have clicked on; only other areas work except the one. How to solve this?

$(document).ready(function()
{
$('#painting').mapster
({
    fillOpacity: 0.5,
    mapKey: 'data-key',

    altImages:
    {
        img1: 'images/image1.png',
        img2: 'images/image2.png'
    },

    render_highlight: 
    {
        stroke: true,
        fill: true
    },
    render_select:
    {
        altImage: 'images/img3.png',
        stroke: false,
        fill: true
    }

});

});

I am calling JS function when clicked on the area (image is not changing; works fine with area2,area3, etc.

function validator()
{
    $('#painting').mapster('set',true,'area1',{altImage: 'img1'});
}

Thanks