ASP .NET MVC 3 Validation unobtrusive - Evaluation order of the validation rules

Question

I have created a custom ValidationAttribute "RequiredIf", to determinate wether a field is empty or not according to another field. I have created the adapter and I have added the method.

Here is the example: http://anthonyvscode.com/2011/07/14/mvc-3-requiredif-validator-for-multiple-values/

The problem is that the property has more metadata than requiredif and the property is Int32, for that if my form is validated on client, firstly it is evaluated if the value is a number and after if the value is empty.

        [Display(Name = "Number of cars")]
        [RequiredIf("IsRent", true, ErrorMessage = "Number of cars is required")]
        [Range(0, 9, ErrorMessage = "Error range")]            
        public virtual Int32? NumberCars
        {
            set;
            get;
        }

How can I fix it?The right order of the rules would be requiredif, number and range.