Automation - update parent

Let me give more detail

activity table(child) have fields (Next follow date and confidence percentage) ,
I have same fields name in parent table (Lead)

I want to keep Last update in Lead table. I'm thinking if I create an automation 
trigger whenever a record added in activity table
action copy next follow date from activity table to lead table
action copy confidence percentage from activity table to lead table

when I'm try to save the action is not allowed . save button not highlight to press and mouse pointer change to circle red with slash.

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Feras Alramli
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