Airtable updating Knack record via Zapier

I am trying to update company information, like company email, when it is modified in Airtable - where it updates the same company record in Knack. Trying through Zapier, but get this error.

What do I do?

To know for sure, would need to see the Set up action section of the Zap step.

It should be searching using a unique value field which is held in both Airtable and Knack (eg company id or similar).


Thanks for replying, Julian. Here is screenshot of the action (need to search first, then update.) What throws me off is the filed key message. I have a business object (object_4) and a business email field (field_20) but do not know how to use this to link the action properly.