TIme Zone error

Hi,

I want to set a specific Timezone for my R environment, with below syntax:

Sys.getenv("Asia/Calcutta")

[1] ""

But it sets to some blank timezone.

I checked with OlsonNames(), to see available zones for R, where I found
"Asia/Calcutta" available.

I idea why R failed to set timezone properly?

Thanks for your time.