Gstream could not find plugins

Today I tried the OAH build of gstreamer and I could compile the hello world example.

But when the code reaches the following lines, it meets a problem:

  source = gst_element_factory_make ("filesrc", "file-source");
  demuxer = gst_element_factory_make ("oggdemux", "ogg-demuxer");
  decoder = gst_element_factory_make ("vorbisdec", "vorbis-decoder");
  conv = gst_element_factory_make ("audioconvert", "converter");
  sink = gst_element_factory_make ("autoaudiosink", "audio-output");

NONE of these elements could be found, but gst-inspect could find all of them.

I turned on the log and it prints out :

0:00:00.062400000 [333m 4904 [00m 005429D0 [32;01mINFO [00m [00;01;37;41m
GST_ELEMENT_FACTORY gstelementfactory.c:484:gst_element_factory_make: [00m no su
ch element factory "filesrc"!

I think it's not the problem of path, because the dlls of gstreamer is in PATH and I put it in the command line parameters to make sure:

--gst-debug-level=3 --gst-plugin-path="C:/Program Files/FOSS/bin"

And I did call gst_init(&argc, &argv) to initialize gstreamer.

Any suggestions?