I can't use my travel credit

[Novianti0]

Hi. I have a problem  in using my travel credit. On the search page all the price have been discounted because i got the travel credit. But when i proceed to check out the price didn't get the discount. Strangely my sister also have the travel credit and she can use it  on the exact same listing. Anyoume has experience this thing and how to apply the travel credit?? 

Thanks

Novi