[pygtk] Strange Assertion

[euro_ii at libero.it]

I have an assertion when i invoke this method:

cur=gtk.gdk.Cursor(self.__pm,
self.__mask,gtk.gdk.color_parse("black"),gtk.gdk.color_parse("white"),5,5)



self.__pm
self.__mask
are two pixmap

assertion:
b"gdk_cursor_new_from_pixmap: 
assertion `GDK_PIXMAP_OBJECT (source)->depth == 1 && GDK_PIXMAP_OBJECT (mask)-
>depth == 1' failed"

I've looking on the net but without any result ...
can 
anyone help me ?


Thank
Matteo