Doubt in Calendar spread

Hi, I have started deploying calendar spreads with one lot. Even though my view is correct, I’m ending up with no profit and paying almost 500 INR as brokerage for all my orders (including adjustments). How can I make calendar spreads profitable? Should I increase the quantity, or is there anything else I should know?

This strategy works brilliantly when the markets moves sideways

Check the IVs of the near week/month and the next week/month. If the IV falls after you create the calendar spread, then you are going to lose money. If the IV increases until you close the trade then you will make profit.