@garimamalhotra,
As Gaureshk_Kodag mentioned, all product detail pages must send in entity values via mbox. The following three parameters would be considered the bare minimum:
entity.id
entity.name
entity.categoryId
Without this information, it is impossible for Recommendations to know what has been viewed or bought.
This is something that should be set up/configured by your developer. With that said, here is a KB article that provides some code examples.
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