验证程序要求的表达性注释出错

这是我的观点

     <div id="Domain">
            <ul class="formlist">
                <li class="width100">
                    <div class="form-check form-check-inline">
                        <label class="form-check-label">
                            @Html.RadioButtonFor(model => model.domain_flag, 1, new { @class = "form-check-input" }) <span>Yes</span>
                        </label>
                    </div>
                    <div class="form-check form-check-inline">
                        <label class="form-check-label">
                            @Html.RadioButtonFor(model => model.domain_flag, 0, new { @class = "form-check-input", @checked = "checked" }) <span>No</span>
                        </label>
                    </div>
                </li>
            </ul>

            <ul class="formlist">
                <li>
                    <div class="frm-marg-b">
                        <label class="label"><b>@Html.LabelFor(model => model.domain_renew_date)</b></label>
                        <div class="textbx">
                            <div class="input-group">
                                @Html.TextBoxFor(model => model.domain_renew_date, new { @type = "datetime", @class = "form-control" })
                                @Html.ValidationMessageFor(model => model.domain_renew_date, "", new { @class = "text-danger" })
                            </div>
                        </div>
                    </div>
                    <div class="frm-marg-b">
                        <label class="label"><b>@Html.LabelFor(model => model.domain_vendor_id)</b></label>
                        <div class="textbx">
                            @Html.DropDownListFor(model => model.domain_vendor_id, Model.domain_Vendor, "Please Select")
                            @Html.ValidationMessageFor(model => model.domain_vendor_id, "", new { @class = "text-danger" })
                        </div>
                    </div>
                </li>
                <li>
                    <div class="frm-marg-b">
                        <label class="label"><b>@Html.LabelFor(model => model.domain_exp_date)</b></label>
                        <div class="textbx">
                            <div class="input-group">
                                @Html.TextBoxFor(model => model.domain_exp_date, new { @type = "datetime", @class = "form-control" })
                                @Html.ValidationMessageFor(model => model.domain_exp_date, "", new { @class = "text-danger" })
                            </div>
                        </div>
                    </div>
                    <div class="frm-marg-b">
                        <label class="label"><b>@Html.LabelFor(model => model.domain_amt)</b></label>
                        <div class="textbx">
                            @Html.EditorFor(model => model.domain_amt, new { htmlAttributes = new { @class = "form-control" } })
                            @Html.ValidationMessageFor(model => model.domain_amt, "", new { @class = "text-danger" })
                        </div>
                    </div>
                </li>
                <li class="width100">
                    <div class="frm-marg-b">
                        <label class="label"><b>@Html.LabelFor(model => model.domain_remarks)</b></label>
                        <div class="textbx3">
                            @Html.TextAreaFor(model => model.domain_remarks, new { htmlAttributes = new { @class = "form-control", @rows = 2 } })
                            @Html.ValidationMessageFor(model => model.domain_remarks, "", new { @class = "text-danger" })
                        </div>
                    </div>
                </li>
            </ul>
        </div>

我的模型

    public int? domain_flag { get; set; }
    [Display(Name = "Date of Renewal")]
    [DataType(DataType.Date)]
    [RequiredIf("domain_flag==1",ErrorMessage ="Enter Renew Date")]
    public DateTime? domain_renew_date { get; set; }
    [Display(Name = "Date of Expiry")]
    [DataType(DataType.Date)]
    [DisplayFormat(DataFormatString = "{0:mm/dd/yy}", ApplyFormatInEditMode = true)]
    [RequiredIf("domain_flag==1", ErrorMessage = "Enter Expiry Date")]
    public DateTime? domain_exp_date { get; set; }
    [Display(Name = "Vendor")]
    [RequiredIf("domain_flag==1", ErrorMessage = "Please Select Vendor")]
    public int? domain_vendor_id { get; set; }
    [Display(Name = "Amount(Rs.)")]
    [RequiredIf("domain_flag==1", ErrorMessage = "Enter Amount")]
    [RegularExpression("^[0-9]+$", ErrorMessage = "Enter Numeric Values")]
    public decimal? domain_amt { get; set; }
    [Display(Name = "Comments")]        
    public string domain_remarks { get; set; }

                     DataAnnotationsModelValidatorProvider.RegisterAdapter(
            typeof(RequiredIfAttribute), typeof(RequiredIfValidator));
        DataAnnotationsModelValidatorProvider.RegisterAdapter(
            typeof(AssertThatAttribute), typeof(AssertThatValidator));