Probably a simple error with my SUMPRODUCT formula (returning VALUE) but I'm stuck!

[Duncasaur]

I'm trying to SUM total sales on a week by week basis for a range of products.
I have a formula I use in a different workbook and it works fine, I've tried adapting it and I cannot for the life of me figure out why it's returning #VALUE! .

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[Kaper]

Basic issue is that your Sales.Sale_Amount is defined as

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while it shall be one column range:

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[Duncasaur]

Thank you! I had a feeling it must be something really daft but I've been trying to figure it out for at least half an hour, clearly needed a fresh pair of eyes (I should probably call it a day if I'm overlooking something like that!)