SQL Problem on finding total weight value

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I am currently stuck on this practice question “What is the total weight in kilograms of orders due in April 2017, or July 2017, or November 2017? Only Include orders which used an unknown shipping method. Find the total weight rounded to 2dp.”

I am stuck trying to use ‘SUM’ to get the total weight and only retrieving ‘UnKnown’ shipping method. The table result however seems to only show UnKnown shipping method without me implementing any code telling it to do so therefore I’m sure if I’m doing this right?