easy gtk-programm fault

[Daniel Dieterle <daniel dieterle ws>]

hallo everybody,

since some days i try to code my first gtk program. it 's not more than 
a window with a label in it.
the code is that:
> #include <gtk/gtk.h>
>
>
> int main( int argc,
>                 char *argv[] )
> {
>         GtkWidget *window1;
>         GtkWidget *label1;
>         
>         gtk_init (&argc, &argv);
>
>         window1 = gtk_window_new (GTK_WINDOW_TOPLEVEL);
>         label1 = gtk_label_new ("Hallo Du");
>
>         gtk_container_add (GTK_CONTAINER (window1), label1);
>         
>         gtk_widget_show (label1);
>         gtk_widget_show (window1);      
>
> //     sleep(1);
> //      gtk_label_set_text (label1,"wie gehts?");
>         
>         gtk_main ();
>
>         return 0;
> }

there is no thing to warry about.
but my aim is to change the text in the label. and if i uncomment the 
"gkt_label_set_text ..."-line, gcc (gcc label.c `pkg-config --cflags 
--libs gtk+-2.0`) shows a warning:
> label.c: In Funktion »main«:
> label.c:22: Warnung: Verarbeiten des Argumentes 1 von »gtk_label_set_text« von inkompatiblem Zeigertyp
which means that the "label1" in the "set_text"-line is a incompatible 
pointertype, i think.

do anybody know, what i'm doing wrong?

thanks,
daniel.