Cannot add notes to final measure
In the last two bars of a long piece, I cannot add notes in those bars. This is an SATB plus Pno format. I CAN add notes in the Soprano, Bass, and Pno staves, but NOT in the Alto and Tenor staves. The S, B, and Pno staves have whole rests in them, indicating that I can add notes. The Alto and Tenor staves have no whole rests in them or anything else. What do I do to fix this?