PopupDateField readonly strange behavior

Hi.
I’m using PopupDatefield with Resolution.MINUTE.
When the app starts the PopupDatefield is in readonly=true state.
If I change this state to readonly=false at runtime and then click the PopupDatefield button the calendar looks like this:

Can’t select hours or minutes, just dates.
It’s strange behavior because if the PopupDatefield is in readonly=false state when de app starts the calendar looks like this:

In this case the component works fine.

Can anyone tell me if something is wrong with my code??

Thanks.

This is my code:

        PopupDateField dfFechaInicio = new PopupDateField();
        dfFechaInicio.setCaption("Fecha Inicio");
        dfFechaInicio.setDateFormat("dd/MM/yyyy HH:mm");
        dfFechaInicio.setResolution(Resolution.MINUTE);
        binder.bind(dfFechaInicio, "fechaInicio");
        dfFechaInicio.setReadOnly(true);