fileselection

["G.Camozzi" <shebby linuxwaves com>]

Hi to alls,
sorry but i'm a newbie with GTK, and i have problem with fileselection.
i have a fileselection window and i put in my callbacks.c this line

void
on_ok_button1_clicked                  (GtkButton       *button,
gpointer         user_data)
{
g_print("%s",gtk_file_selection_get_filename(
GTK_FILE_SELECTION(user_data) ));

}

On my output i have this error:

Gtk-WARNING **: invalid cast from (NULL) pointer to `GtkFileSelection'

Gtk-CRITICAL **: file gtkfilesel.c: line 2487
(gtk_file_selection_get_filename): assertion `filesel != NULL' failed.

How can i print the result of selection in fileselection window?

Sorry my english is very bad!

Thanks a lot