HDFC card being rejected by both Amazon and Flipkart

Hello all, I am not able to use my HDFC regalia credit card on both amazon and flipkart. On flipkart I am getting the following message after adding my card.

And on amazon I am getting the following message

However, the card is working for small transaction amount like 300-500 on amazon.

All other cards of mine are working fine.

Anybody  has any idea regarding why this is happening?