Sum with reference table as a filter

[maverik88]

Hi, i was not able to sum up values filtered by a reference table unique values. I've a Project table where i record construction work hours. The reference table is called location. Seems basic, but i've tried many formulas but none of them are working. I've tried Google Gemini but it always gives bad formulas. Any insight will be much appreciated. 

Thanks 

[AleksiAlkio]

So.. you have two tables, Project (parent) and Location (Child), right?
#1 - What column are you trying to sum and in which table that column is?
#2 - In which table are you trying to sum this?