HELP: Cannot draw glyph, using gdk_draw_layout()

["dozen" <dozenlue tom com>]

Hi, all
    I use gdk_pango_context_get() to get a PangoContext,
    and pango_layout_new() to get a layout
    and pango_layout_set_text() to set text to render.

    Then, I set the background color of the pango layout to be red,
set the foreground color to be green, and set underline.
    After I call gdk_draw_layout(), I get a red box(the background)
with a green underline.
    But the glyphs are not drawn... @_ ?

    My question is:
        1. Is there any status error in GdkDrawable and GdkGC could cause
           this problem?
        2. If not, where the root cause can be? or, how to correct it?

    Thanks you!