error site register django

Question

I have two classes in my admin.py. Because I can't register them twice, I don't know how to fix my problem. It says: "register() takes at most 3 arguments (4 given)". This is my code:

class Tesi_AvailableAdmin (admin.ModelAdmin):
    model=Tesi
    fieldsets = (
            (None, {
                   'fields': ('Teacher', 'Title', 'Description', 'Date')
                    }),
             )


    list_filter = ['Date']
    search_fields = ['Teacher', 'Title', 'Description']

    def queryset(self, request):
        qs=super(Tesi_AvailableAdmin, self).queryset(request)
        return qs.filter(State='Available')

class Tesi_RequestAdmin (admin.ModelAdmin):
    models=Tesi
    fieldsets = (
     (None, {
        'fields': ('Teacher', 'Title', 'Description', 'Date', 'Student')
         }),
    )
    list_filter = ['Date']
    search_fields = ['Teacher', 'Title', 'Description'] 

    def queryset(self, request):
        qs=super(Tesi_RequestAdmin, self).queryset(request)
        return qs.filter(State='Request')

admin.site.register(Tesi,Tesi_AvailableAdmin)
admin.site.register(Tesi_RequestAdmin)

Do you know how I can register all the classes? Thank you!