Why transaction revenue from google search result go to Direct not Organic Search?

Question

I'm little confused in google analytics channel.

I'm trying to check out a product on my website but why is the revenue going to Direct instead of Organic Search?

The way I check out the product is as follows:

1. Google search "my website"
2. click link on google search result
3. checkout
4. transaction.

Why does revenue go to Direct and not to Organic Search?

Can anyone help me?