NOT(ISBLANK()) partially working

[MrDarcy]

Alright here is what I'm doing.
I have 4 worksheets, the top being a cover sheet
Using conditional formatting I want a range of cells on the front page to highlight if the corresponding cell on one of the other cells is filled in.
On the front sheet I'm using the following (or something similar):
=NOT(ISBLANK(Sheet3!C4:C9))
The formula is working in some columns but doesn't work for the values in the C and D columns on the front sheet.
I moved the formula calling the same cells but in the A and B columns and it works correctly.
Can anyone explain why the formula is not working in the C & D columns and how to fix it?

 

[Candyman8019]

what data is in Sheet3!C4:C9? What error are you getting?

 

[MrDarcy]

The data for the other sheets is a date, but I've tested with numbers and characters as well.
No error but the associated cells will not format (highlighting) or they will not remove the highlight when you delete the data in the other cell.

 

[Fluff]

Try it like

=Sheet3!C4<>""

 

[MrDarcy]

Try it like

=Sheet3!C4<>""

Okay can you explain to me why that works in these particular columns where the other formula didn't?
Yes that seems to have resolved the issue

 

[MrDarcy]

Okay can you explain to me why that works in these particular columns where the other formula didn't?
Yes that seems to have resolved the issue

I spoke too soon, it resolved 1 section but still having the same issue with data from a different sheet. Yes, I updated it and cleared the old formula.

 

[Candyman8019]

I can't think of a reason why that formula wouldn't work. Try doing a 'clear all' for the cells in C4:C9...there may be something odd with those cells.

 

[Fluff]

still having the same issue with data from a different sheet

Maybe the cells are not totally empty.

 

[MrDarcy]

I've cleared the cells about 5 times and re-re-re-re-done the various formulas. It seems to be working at the moment, but I don't like not knowing what is going on.
Thanks for the thoughts.

 

[Fluff]

re-re-re-re-done the various formulas.

Are those formulae in the cells that the CF is looking at?