isNull in expression binding with no effect

Ignition 7.9.2-RC1
I have the following code in an texte expression binding :

if(isNull({SYS_SERVER_GTC.ContainerServer.LabelDate.dateProp}), "", try(dateFormat(toDate({SYS_SERVER_GTC.ContainerServer.LabelDate.dateProp}), "yyyy/MM/dd HH:mm:ss"),"?"))

When I open the windows in the vision client, the following error occurs:
15:31:16.286 [AWT-EventQueue-2] WARN Expressions.DateFormatFunction - ‘dateFormat’ function expected a ‘date’ first argument, but got null

The value displayed is good but it seems that isNull don’t do is job :worried:

I was able to replicate your error by giving the tag a non-null value that’s not a date. This made isNull return false, but toDate return null. Perhaps that’s your problem?

{SYS_SERVER_GTC.ContainerServer.LabelDate.dateProp} is a custom String propertie binded to a String tag which is not Null. The tag is a memory with a string formatted “yyyy/MM/dd HH:mm:ss”. I have the error in the client when I open the windows, I suppose it is a transitory issue because the value displayed is OK ???

I will try this to avoid the transitory log error :

try(dateFormat(toDate({SYS_SERVER_GTC.ContainerServer.LabelDate.dateProp}), "yyyy/MM/dd HH:mm:ss"),"?"))