无法在MKMapview上的两个位置之间绘制路径

Question

我正在尝试从当前源绘制路径到目的地和方向完成处理程序，我收到错误

Domain = MKErrorDomain Code = 5“方向不可用”

我现在正在使用iOS 7。

这是我的代码

MKDirectionsRequest *DirectionRequest = [[MKDirectionsRequest alloc]init];
MKPlacemark *QiblaPlace = [[MKPlacemark alloc]initWithCoordinate:CLLocationCoordinate2DMake(21.4166667, 39.81666670000004) addressDictionary:nil];
[DirectionRequest setSource:[MKMapItem mapItemForCurrentLocation]];
[DirectionRequest setDestination:[[MKMapItem alloc] initWithPlacemark:QiblaPlace]];
DirectionRequest.transportType = MKDirectionsTransportTypeAutomobile;
DirectionRequest.requestsAlternateRoutes=YES;
MKDirections *direction = [[MKDirections alloc]initWithRequest:DirectionRequest];
[direction calculateDirectionsWithCompletionHandler:^(MKDirectionsResponse *response, NSError *error) {
    if (error) {
        NSLog(@"Error %@", error.description);
    } else {

        routeDetails = response.routes.lastObject;
        for (MKRoute *route in response.routes) {
            [_routeMapview addOverlay:routeDetails.polyline level:MKOverlayLevelAboveRoads];
        }
    }
}];

感谢您的帮助。