var _extension_list;
var _total_extension;
function extensionSelectionCheck(source, value){
    
    var control;
    
    for (i=0;i<_total_extension;i++){
        control = document.getElementById(_extension_list + '_' + i);
        
        if (control.checked == true){
            value.IsValid = true;
            return true;
        }
    }
    
    value.IsValid = false;
    return false;
}