SUMIFS Lock

I always have this trouble with knowing where to lock my cell reference. I have attached my mock data. In the summary tab, I need to populate by each date D-Q, by product (C) and by Region (B), what the numbers are.. Data is in the first tab. I did the first column. I have tried multiple times, changing the cell reference but can't get it to give me my output. I also have blanks in some regions. Can you please help? Also, what's a good to remember what to lock? I am familiar with absolute but always have this issue.

Worksheet name : Summary
Cell D2 formula , Drag down and across

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