I tried so many hours and I put all the versions but I did not find the solution . Can you help me to understand the problem of not working

Expected behavior

Actual behavior

Resources (screenshots, code snippets etc.)

<form asp-action="Create" class="needs-validation" required>
<div class="row mt-5">
    <div asp-validation-summary="ModelOnly" class="text-danger"></div>
</div>
<div class="row">
    <partial name="_PostSteps" />
    <div style="display:none;">
        <div class="form-group hide">
            <input type="hidden" asp-for="Post.Active" class="form-control" value="false" />
            <input type="hidden" asp-for="Post.StateOfPost" class="form-control" value="1" />
            <input type="hidden" asp-for="Post.OwnerId" class="form-control" value="1" />
        </div>
    </div>
    <div id="parentForm" class="col-sm-8">
        <div id="initial-submit" class="card card-cascade narrower">
            <div class="view view-cascade gradient-card-header blue-gradient">
                <h4 class="font-weight-500 mb-0">@SharedLocalizer.GetLocalized("Υποχρεωτικά Στοιχεία")</h4>
            </div>
            <div class="card-body card-body-cascade">
                <div class="row">
                    <div class="md-form col-lg-6 col-md-12">
                        <label for="inp_Category">
                            @SharedLocalizer.GetLocalized("Τύπος Αγγελίας")
                        </label>
                        <select id="inp_Category" aria-label="Κατηγορία" class="mdb-select mdb-select-required" name="Post.SaleCategory">
                            <option value="Πώληση">@SharedLocalizer.GetLocalized("Πώληση")</option>
                            <option value="Ενοικίαση">@SharedLocalizer.GetLocalized("Ενοικίαση")</option>
                            <option value="Ζήτηση">@SharedLocalizer.GetLocalized("Ζήτηση")</option>
                        </select>
                        <div class="invalid-feedback">
                            Please provide 
                        </div>
                    </div>
                    <div class="md-form input-group col-lg-6 col-md-12 mb-3">
                        <input type="text" class="form-control" asp-for="Post.PriceTotal" aria-label="Αξία">
                        <label class="form-check-label ml-3" for="Post_PriceTotal">
                            @SharedLocalizer.GetLocalized("Τιμή Ακινήτου")
                        </label>
                        <div class="input-group-append">
                            <span class="input-group-text md-addon">.00</span>
                        </div>
                        <div class="input-group-append">
                            <span class="input-group-text md-addon">€</span>
                        </div>
                        <div class="invalid-feedback">
                            Please provide 
                        </div>
                    </div>
                </div>