hi i'm googling around about this problem but i didn't find any usfull about this.

I want to deni the set of an property if the Validation per DataAnnotations fails

Could you please tell me what i miss in my code?

Model Codesnip

        private string _firstname;
        public string Firstname
        {
            get { return _firstname; }
            set
            {
                _firstname = value;
                RaisePropertyChanged(() => Reg(() => Firstname));
            }
        }

ViewModel Codesnip

        [Required]
        [RegularExpression(@"^[a-zA-ZäöüßÄÖÜß''-'\s]{2,40}$")]
        public string Name
        {
            get { return currentperson.Name; }
            set
            {
                currentperson.Name = value;
            RaisePropertyChanged(() => Reg(() => Name));
            }
        }

View Codesnip

<TextBox HorizontalAlignment="Left" VerticalAlignment="Top" Width="120" Text="{Binding Firstname,UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True}"/>

any help would be greatly appreciated