Druk Air's "Flight Schedule via SMS"

The Druk Air website claims that you can "know flight timing" by sending an SMS message to 2121, with text depending on the day of week:

Monday type INFOMON and send it to 2121,
Tuesday type INFOTUE and send it to 2121,
Wednesday type INFOWED and send it to 2121,
Thrusday type INFOTHU and send it to 2121,
Friday type INFOFRI and send it to 2121,
Saturday type INFOSAT and send it to 2121
Sunday type INFOSUN and send it to 2121.

I tried it from my TashiCell, but received the error message: "Your message sent to 2121 could not be completed. Please try again later." I tried again later and received the same error message.

Has anyone used this service successfully? Any tips appreciated.