gtk_tree_model_sort_real_unref_node and gtk_tree_model_filter_real_unref node critical

[Nicolas Soubeiran <nicolas soubeiran gmail com>]

Hello all,
I'm writing a binding for GTK+ to use the GtkTreeView. I sometime
have, when I select a row in a GtkTreeView that display a
sorted-filtered model (i.e the model displayed is a GtkTreeModelSort
whose child is a GtkTreeModelFilter whose child is a GtkListStore) 2
GTK-Critical :
gtk_tree_model_sort_real_unref_node  : assertion elt->ref_count > 0 failed
gtk_tree_model_filter_real_unref node : assertion elt->ref_count > 0 failed

I do not know what these errors mean and how I can avoid/remove them.
Can anybody help please?