Unexplainable Value error. Data type/links/formula is correct.

[TinyDamooge]

Hi all, I was hoping I could have some help with a big problem I've been having.

I use a SUM formula to collect data (hours) from many single spreadsheets and sum them into the summary spreadsheet.

This works fine, but then for one particular cell it doesn't work.
I can't understand why,
I've checked all the links are not broken,
I've checked the cell format is correct.
I've been into every singular spreadsheet and checked the data type is correct (hours, so numerical).
The formula works in every other cell and is simply dragged to spread into every other cell.

Just this one cell returns a value error.


See the attached picture of my summary spreadsheet for clarity, though I had to sanitize it heavily.

spreaderror.png

Cheers for any help you can give with this.