Fixed Functions along with Case statements


in the below data i require the sum of Value 2 when the sum of value 1 for the distinct values in the key column is greater than 0

the expected answer for the below will be 1+2+5+6 = 14

i can derive the SUM of value 1 by using the fixed function

SUM(SUM(`Value1`) FIXED(By `Key`))

However, when i wrap it inside a Case statement to SUM the Value 2 Colum where the Fixed sum of Value 1 is greater than 0 the evaluation fails

I have tried both the below variation , both fail at evaluation