saveImage in swf fail

[friendvn2000]

I have a map file that outputs swf format... I use PHPMapScript to implement:

$map = ms_newMapObj("test.map");
$image=$map->draw();
$image_url=$image->saveWebImage();

It generates some random name swf files like:

47ba3cf0_d1c_0.swf
47ba3cf0_d1c_0_layer_0.swf
47ba3cf0_d1c_0_layer_1.swf

But I want to save them as normal name, so I do next:

$image->saveImage("img_gen/test.swf");

and it works when saving them to those files:

test.swf
test_layer_0.swf
test_layer_1.swf

But in the test.swf file, the links to its child layers not change, so I can't use them !

( Maybe it's a MapServer's fatal error )

Thanks.