My script doesn´t open fileselector

I am adapting my onw old script but i don´t achieve to open fileselector to read data from a custom file


import bpy


	
class ExportSomeData(bpy.types.Operator):
    bl_idname = "Open_CFF_File"
    bl_label = "Open CFF"

    filepath = bpy.props.StringProperty(subtype="FILE_PATH")

    @classmethod
    def execute(self):
       file = open(self.filepath,"r")
	   header = file.readline()    
	   if header != '//Ciber Face Converter File (c)2009 by Jor1980
':
		Blender.Draw.PupMenu('This is not a *.cff file')
		print (header)
		file.close()
        return {'FINISHED'}	
    
    def invoke(self, context, event):
        context.window_manager.fileselect_add(self)
        return {'RUNNING_MODAL'}


	
# Register and add to the file selector
bpy.utils.register_class(ExportSomeData)
bpy.types.INFO_MT_file_export.append(menu_func)


# test call
bpy.ops.Open_CFF_File('INVOKE_DEFAULT')



def load_data(file):
	
	file.next()
	CffType=file.next().replace('Type=','')
	Scene_Name=CffType
	sc=Scene.New(Scene_Name)
	sc.makeCurrent()
	#sc = Scene.GetCurrent()
	screen_list = Window.GetScreens()
	for screens in screen_list:
		Window.SetScreen(screens)
		sc.makeCurrent()
	Window.SetScreen(screen_list[0])
	numeroparts=int(file.next().replace('Number of blocks=',''))
    
	numerovertxpart=[]
	numerofacexpart=[]
	file.next()
	
	
	
	for i in range(0,numeroparts):
		line=file.next()
		print (line.split()[0])
		print (line.split()[1])
		numerovertxpart.append(int(line.split()[0]))
		print (numerovertxpart[i])
		numerofacexpart.append(int(line.split()[1]))
		print (numerofacexpart[i]) 	
	
	
	
	
	
	

	
	malla=[]
	ob=[]
	for i in range(0,numeroparts):
		malla.append(bpy.data.meshes.new("2K_Part"))
		uv = []
	
		for j in range(0,numerovertxpart[i]):
			line=file.next()
			x,y,z,u,v=float(line.split()[0].replace(',','.')),float(line.split()[1].replace(',','.')),float(line.split()[2].replace(',','.')),float(line.split()[3].replace(',','.')),float(line.split()[4].replace(',','.'))
			uv.append((u,v))
			print (x,y,z)
			malla[i].verts.extend(float(x),float(y),float(z))
		
		aa = []
		bb = []
		cc = []
	
		
		for j in range(0,numerofacexpart[i]):
			line=file.next()
			a,b,c=int(line.split()[0]),int(line.split()[1]),int(line.split()[2])
			aa.append(a)
			bb.append(b)
			cc.append(c)
			print (a,b,c)
			bface = Blender.NMesh.Face()
			bface.v.extend((a,b,c))
			malla[i].faces.extend(bface)
			
		malla[i].faceUV = True
	
	
		for q in range(len(malla[i].faces)):
			malla[i].faces[q].mode |= Blender.Mesh.FaceModes['TWOSIDE']
			malla[i].faces[q].transp = Blender.NMesh.FaceTranspModes['ALPHA']
			malla[i].faces[q].uv=Mathutils.Vector(uv[aa[q]]), Mathutils.Vector(uv[bb[q]]), Mathutils.Vector(uv[cc[q]])
	
		
		
		scn = bpy.data.scenes.active
		ob.append(scn.objects.new(malla[i], CffType))
		ob[i].modifiers.append(Modifier.Types.SUBSURF)
		ob[i].modifiers.append(Modifier.Types.SUBSURF)