SSRS IsNothing finding something

Having a small problem with the logic for the Hidden property. Probably not specific to Hidden, but that is where I am using it.

We have added tracking number to the AR invoice.

The expression that is displayed in the header is:

="Tracking Number: " & First(Fields!ShipHead_TrackingNumber.Value)

We prefer to have nothing displayed if there is no tracking number, so the Hidden property is set to:

=IIf(IsNothing(First(Fields!ShipHead_TrackingNumber.Value)) = True,True,False)

This, to me, says that if ShipHead_TrackingNumber is Null, hide the expression. However, what we are seeing is "Tracking Number: ".

How do I hide the whole expression?

I think the IsNothing expression is going to give you your Boolean for the Iif expression. Therefore, the = TRUE is not needed. Have you tried without this?

The code below returns the same: "Tracking Number " without any data

=IIf(IsNothing(First(Fields!ShipHead_TrackingNumber.Value)),True,False)

Okay cool. So perhaps the data is coming across as ‘Blank’ rather than NULL. Have you tried an expression for ‘Blank’ evaluation as opposed to or including NULL?

And the winner is…

=IIf(First(Fields!ShipHead_TrackingNumber.Value) = “”,True,False)

Thanks @Michael_Ramsey for helping me think about it.

You are very welcome.