Issue with Error Message when nothing selected from Date interface Tool

[Mboti]

Hi Everyone,

I have a problem with my analytic app, because I want to show an error message when the user do not select anything from the date tool or from the ListBox tool, but i don't know how to do it.
I thought the Error Message tool will help me out with  this expression: "IsEmpty([#1])". But do not really work.

Is there any way to display an error message when the user do not select anything from the interface tools?

Thank you in advance for your help.

[alexnajm]

The Date interface tool defaults to today's date so I don't think it can ever be empty! Is there another test you can do for the Date interface?

[Mboti]

Okay, great it make sense, thank you :)
And what about the ListBox tool, can you help me out?
I think it doesn't have a default value, so is there any way, I can check if it's empty or throw an error message when the user do not choose anything from the ListBox tool ?

Thank you in general