Why did Vasco da Gama fail to make a trade treaty at Calicut in 1498?

Vasco da Gama failed to secure a trade treaty at Calicut in 1498 due to a combination of diplomatic, cultural, and economic factors.1

His efforts were hindered by the following:

• Hostility from established merchants: Muslim Arab merchants, who were already well-entrenched in the region's trade, actively opposed the Portuguese presence.12
• Inadequate trade goods: The gifts and trade items da Gama brought were suited for West African markets and were considered "trumpery" or of little value to the sophisticated Indian market.1
• Poor diplomatic conduct: Da Gama’s own rude behavior further alienated the Zamorin, the Hindu ruler of Calicut, effectively dispelling any initial welcome he might have received.1
• Cultural misunderstandings: The Portuguese arrived with the mistaken belief that the local Hindu population were Christians, which complicated their initial diplomatic approach.1

These failures, compounded by da Gama's lack of local knowledge, ultimately prevented the establishment of a formal agreement during his first voyage.1