casper.start的循环仅执行一次

我使用以下脚本循环页面的选项以获取后续值:

var casper = require('casper').create();
casper.on('remote.message', function (message) {
    this.echo(message);
});
casper.on( 'page.error', function (msg, trace) {
    this.echo( 'Error: ' + msg, 'ERROR' );
});
casper.start(url, function() {
    this.evaluate(function() {
        // nothing
    });
    this.then(function() {
        ddlArea_options = this.getElementsAttribute('#ddlArea option', 'value');
        for(var i = 0; i < ddlArea_options.length; i++) {
            if(ddlArea_options[i] != '') {
                this.echo(ddlArea_options[i]);
                startQuery('myID', ddlArea_options[i]);
            }
        }
    });
});

哪里 startQuery(id, val) 函数是否包含 casper.start() :

function startQuery(id, val) {
    casper.start(url, function() {
        this.echo('startQuery started');
        var obj = {};
        obj['#' + id] = val;
        this.fillSelectors('#form1', obj, true);
        this.evaluate(function() {
            __doPostBack('ddlArea', '');
        });
        this.then(function() {
            this.echo("doPostback complete");
            var values = this.getElementsAttribute('#anotherSelect option', 'value');
            for(var i = 0; i < values.length; i++) {
                this.echo(values[i]);
            }
        });
    });
    casper.run();
}

但是 startQuery() 仅对for循环中的最后一项执行一次。我错过了什么?