Here is a piece of my code:

....
if (sel_artist_name)
gtk_entry_set_text(GTK_ENTRY(entry_artist_name), sel_artist_name);
else
gtk_entry_set_text(GTK_ENTRY(entry_artist_name), "");

if (sel_album_title)
gtk_entry_set_text(GTK_ENTRY(entry_album_title), sel_album_title);
else
gtk_entry_set_text(GTK_ENTRY(entry_album_title), "");
....

sel_artist_name and sel_album_name are defined as char *, while entry_* are GtkEntry widgets.
Knowing that sel_* pointers points to a dynamically allocated strings, and the widgets are valid, why I can't set a text to entry_album_title? It seems that ignore me!

I analysed the program with gdb, and it work correctly, but the album title is not displayed... why?

I don't think you should have other source code... What I want to know is the reason of the blank text entry after the line

gtk_entry_set_text(GTK_ENTRY(entry_album_title), sel_album_title);

if sel_album_title contains a valid string!

Thank you.