Summing the peak power of entire house in a statistics card

Configuration
1

I’m looking into this for 2 hours now.
I want to have a graph that tells me my peak power usage, but the sum is not working in the Statistics Graph Card

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image791×1611 99.3 KB

Why is this not working? The Sum is greyed out.

2

Expected data source not listed - Home Assistant (home-assistant.io)