Past Perfect Tense Question

I ________(reply) to his letter two weeks ago, but he ____________(never receive) it. That ___________(be) why he ________(write) to me again, asking why I ___________ (not reply) to his letter.

I replied to his letter two weeks ago, but he never received it. That was why he wrote to me again, asking why I had not replied to his letter.

Please tell me if my answers are correct and suggest any alternative answers. thanks