Yep, I think you have found out your own error here. Olive Oil which is great for everyday cooking and also good for us is a no-no in curry cooking. It does have a lower "smoking point" and an Oil with higher heating properties is needed. Restaurants and Take-away's use mainly Veg Oil and I don't use anything else except maybe Sunflower Oil or Vegetable Ghee. In Chinese cooking they use Groundnut Oil (peanut oil) which seems to have about the highest smoking point of all.
Ray