Use of DATEIF Function

[Marcie Be]

I am using the DATEIF function to stop counting the numbers of days open when a closed date is input in another cell.
I also need the formula to work when the cell with the creation date is blank.
Here is my Formula
AA=DATEDIF($Z4,IF(H4>0,H4,TODAY()),"D")

If Cell $Z4 is empty i.e. there is no creation date the cell AA should be blank/empty

Should I use the OR Function? If so how?

 

[Marcie Be]

You're welcome, glad you resolved it

It is not resolved yet, but I appreciate your help to get this far.
The formula now does not work if there is a date in $AA4
$AB4 shows zero when it should show a number

 

[Fluff]

Maybe
=IF($AA4="","",DATEDIF($AA4,IF($H4>0,H4,TODAY()),"D"))

 

[Marcie Be]

Maybe
=IF($AA4="","",DATEDIF($AA4,IF($H4>0,H4,TODAY()),"D"))

Hooray, that has worked.
BIG THANK YOU Fluff and @JackDanIce too.

 

[Fluff]

Glad we could help & thanks for the feedback.