BeanValidator don't fire (I believe)

I’ve a Form in wich create 3 text fields one of them is annotated as @NotNull in the Bean a BeanValidator is created and added.
However I don’t see the small red asterisk on the field and thevalidator doesn’t fire when I leave the field empty
The same happens in another field annotated with @Size.
What’s wrong ?
Tks

I tested a little deeper and the situation is different.
The validator is called and finds the @NotNull, however the value to be validated is not null but an empty string and then it validates against NonNulll.
Is it a bug ?
How can I solve it ?
Tks
Tullio

Another problem, after an error (I tested size constraint) the exception is catched somewhere and the process do not stop if I click a button.
The message is shown but the process still goes further.
Tks
Tullio

Nobody can help ?
Tks
Tullio