SumProduct and Weekday problem

Attach a sample workbook. Make sure there is just enough data to demonstrate your need. Include a BEFORE sheet and an AFTER sheet in the workbook if needed to show the process you're trying to complete or automate. Make sure your desired results are shown, mock them up manually if necessary.

Remember to desensitize the data.

Click on GO ADVANCED and use the paperclip icon to open the upload window.

View Pic

thanks guys, I have attached a sample spreadsheet, de-sensitized, but I think the problem may be the blanks as mentioned by Boopathirajah, but that solution doesn't work!

oops , forgot to mention, it's the 'other graphs' tab, and only one cell is misbehaving! this is why it's confounding!
am aware of the circular reference warning, but I don't think it affects the data - and as I said, it's not my spreadsheet but somebody else's that I have been asked to fix!