Как в asp.net сделать кнопку недоступной до тех пор, пока форма не пройдёт валидацию?

Примерно так:

    protected void Wizard1_NextButtonClick(object sender, WizardNavigationEventArgs e)
    {
        if (e.CurrentStepIndex == 0)
        {
            bool IsValidPassword = false;
            ///
            /// Validate user
            ///
            if (!IsValidPassword) e.Cancel = true;
        }
    }
    public bool IsValidPassword
    {
        get
        {
            return Valid.password(password.Text) &&
                   Valid.password(repassword.Text);
        }
    }
public class Valid
    {
        public static bool email(string email)
        {
            string pattern = "[.\\-_a-z0-9]+@([a-z0-9][\\-a-z0-9]+\\.)+[a-z]{2,6}";
            Match isMatch = Regex.Match(email, pattern, RegexOptions.IgnoreCase);
            return isMatch.Success;
        }
        public static bool username(string username)
        {
            string pattern = "[a-zA-Zа-яА-Я0-9]{5,50}";
            Match isMatch = Regex.Match(username, pattern, RegexOptions.IgnoreCase);
            return isMatch.Success;
        }
        public static bool password(string password)
        {
            string pattern = "(^[a-zA-Zа-яА-Я0-9-~!@#$%^&?*]{6,20})$";
            Match isMatch = Regex.Match(password, pattern, RegexOptions.IgnoreCase);
            return isMatch.Success;
        }
        public static bool lfName(string LastFirstName)
        {
            string pattern = "[a-zA-Zа-яА-Я]{2,50}";
            Match isMatch = Regex.Match(LastFirstName, pattern, RegexOptions.IgnoreCase);
            return isMatch.Success;
        }
        public static bool probel(string LastFirstName)
        {
            string pattern = "([\\s])";
            Match isMatch = Regex.Match(LastFirstName.Trim(), pattern, RegexOptions.IgnoreCase);
            return isMatch.Success;
        }
        public static bool phone(string phone)
        {
            string _phone = phone;
            _phone = Regex.Replace(_phone, @"[^\d]", "", RegexOptions.Compiled);
            string pattern = "([0-9]{10})$";
            Match isMatch = Regex.Match(_phone, pattern, RegexOptions.IgnoreCase);
            return isMatch.Success;
        }
        public static bool address(string address)
        {
            string pattern = "^[a-zA-Zа-яА-Я0-9-.,\\s]{5,300}$";
            Match isMatch = Regex.Match(address.Trim(), pattern, RegexOptions.IgnoreCase);
            return isMatch.Success;
        }
        public static bool sity(string sity)
        {
            string pattern = "^[a-zA-Zа-яА-Я-]{2,40}$";
            Match isMatch = Regex.Match(sity.Trim(), pattern, RegexOptions.IgnoreCase);
            return isMatch.Success;
        }
        public static bool index(string index)
        {
            string pattern = "^[0-9\\s]{3,10}$";
            Match isMatch = Regex.Match(index.Trim(), pattern, RegexOptions.IgnoreCase);
            return isMatch.Success;
        }
    }