Ordinarily, one who forgot to pray 'Arbith would have to pray the silent Shahrith 'Amidah twice, the first for...
Wednesday, November 30, 2011/Kislew 4, 5772

Tashlumin (praying a make up 'Amidah for one that was missed) can only be done during the next prayer. If one did...
Tuesday, November 29, 2011/Kislew 3, 5772