undefined reference ! Help !

["schmirrwurst free fr" <schmirrwurst free fr>]

Hi, 
I'm  pretty new, and I'm trying to add some functionality to gparted...
By compiling I get an error, it seems that my function is not properly
declared, but I can't find the mistake ! Can somebody help me ?

      * Here is the error message : 
      * -------------------------------------------------------------------------
Win_GParted.o: In function
`GParted::Win_GParted::activate_make_image()':
/home/wsb/Projects/gparted/src/Win_GParted.cc:1799: undefined reference
to `GParted::Dialog_Make_Image::Dialog_Make_Image(GParted::Partition
const&)'
collect2: ld returned 1 exit status
      * ---------------------------------------------------------------------------
      * Here is the function in Win_GParted.cc
      * ---------------------------------------------------------------------------
void Win_GParted::activate_make_image() 
{
	get_window() ->set_cursor( Gdk::Cursor( Gdk::WATCH ) ) ;
	while ( Gtk::Main::events_pending() )
		Gtk::Main::iteration() ;

	Dialog_Make_Image dialog( selected_partition ) ; //line 1799
	dialog .set_transient_for( *this ) ;
	/*dialog .signal_get_flags .connect(
		sigc::mem_fun( &gparted_core, &GParted_Core::get_available_flags ) ) ;
	dialog .signal_toggle_flag .connect(
		sigc::mem_fun( &gparted_core, &GParted_Core::toggle_flag ) ) ;
	*/
	get_window() ->set_cursor() ;
	
	dialog .run() ;
	dialog .hide() ;
	
}
      * ---------------------------------------------------------------------------
      * Here is Dialog_make_image.h : 
      * ---------------------------------------------------------------------------
Here is Dialog_make_image.h : 
#ifndef DIALOG_MAKE_IMAGE_H
#define DIALOG_MAKE_IMAGE_H

#include "../include/Partition.h"

#include <gtkmm/dialog.h>
#include <gtkmm/treeview.h>
#include <gtkmm/liststore.h>

namespace GParted
{
	
class Dialog_Make_Image : public Gtk::Dialog
{
public:
	Dialog_Make_Image( const Partition & partition );

	sigc::signal< std::map<Glib::ustring, bool>, const Partition & > 
signal_get_flags ;

sigc::signal< bool, const Partition &, const Glib::ustring &, 
bool > signal_toggle_flag ;

private:	
	Partition partition ;
};//class

} //GParted


#endif //DIALOG_MAKE_IMAGE_H
      * ---------------------------------------------------------------------------
      * Here is Dialog_make_image.cc : 
      * ---------------------------------------------------------------------------
#include "../include/Dialog_Make_Image.h"

#include <gtkmm/main.h>
#include <gtkmm/stock.h>
#include <gdkmm/cursor.h>
 
namespace GParted
{
	
Dialog_Make_Image::Dialog_Make_Image( const Partition & partition )
{
	set_title( String::ucompose( _("Make an image from partition %1"),
partition .get_path() ) );
	set_has_separator( false ) ;
	set_resizable( true ) ;

	Glib::ustring str_temp = "<span weight=\"bold\" size=\"larger\">" ;
	str_temp += String::ucompose( _("Choose target image file for the %1
backup"), partition .get_path() ) ;
	str_temp += "</span>\n" ;
	get_vbox() ->pack_start( * Utils::mk_label( str_temp ),
Gtk::PACK_SHRINK );
	
	add_button( Gtk::Stock::CLOSE, Gtk::RESPONSE_OK ) ->grab_focus() ;

	show_all_children() ;
	this ->partition = partition ;
	
} //class
	
}//gparted