高德地图JavaScript API 获取不到路线

var searchWays = $('#searchWays');
    var start = $('#startspot').val();
    var end = $('#endspot').val();
    var map = new AMap.Map('mapContainer', {
        resizeEnable: true
    });
    var drivingOption = {
        policy: AMap.DrivingPolicy.LEAST_TIME
    };
    var driving = new AMap.Driving(drivingOption);
    searchWays.on('click',function(){
    driving.search([{keyword: start},{keyword: end}]
     ,function(status,result){
        if(status==='complete' && result.info==='OK'){
            (new Lib.AMap.DrivingRender()).autoRender({
                data: result,
                map: map,
                panel: 'mapPanel'
            });
        }else{
            alert(result);
        }
    });

把关键字写进去路线是可以出来的，但是用变量获取，再传进去却什么都出不来，，求解？？？