Error filling table with datatable jquery ajax ASP.NET

<div class="card">
    <div class="card-body">
        <h5 for="txtLista" class="form-label">Integrantes</h5>
        <table id="tabla" class="display cell-border" style="width: 100%">
            <thead>
                <tr>
                    <th>Nombre</th>
                    <th>Fecha nacimiento</th>
                    <th>Edad</th>
                    <th>Sexo</th>
                    <th>Tipo documento</th>
                    <th>Numero documento</th>
                    <th>Editar/Eliminar</th>
                </tr>
            </thead>
            <tbody>
            </tbody>
        </table>
    </div>
</div>

@section scripts{
    <script>
	var tabladata;
	var filaseleccionada;

	$(document).ready(function () {
    	   $("<option>").attr({ "value": "0", "disabled": "disabled", "selected": "true" }).text("Seleccionar").appendTo("#cbbunidad");
    	   jQuery.ajax({

        	url: "@Url.Action("ListarUnidad", "Mantenedor")",
        	type: "GET",
        	datatype: "json",
        	contentType: "application/json; charset=utf-8",
        	success: function (data) {

            		if (data.data != null) {
                		$.each(data.data, function (index, item) {
                    			$("<option>").attr({"value":item.uniId}).text(item.uniNombre).appendTo("#cbbunidad");
                		})
            		}
        	},
        	error: function (error) {
            		console.log(error)
        	}
    	    });
	})

	$("#btnBuscar").on("click", function () {

            tabladata = $("#tabla").DataTable({
                destroy: true,
                responsive: true,
                ordering: false,
                "ajax": {
                    url: "@Url.Action("ListarIntegrantesUnidad", "Mantenedor")",
                    type: "POST",
                    datatype: "json",
                    contentType: "application/json; charset=utf-8",
		    data: JSON.stringify({ idunidad: $("#cbbunidad option:selected").val() })
                },
                "columns": [
                    { "data": "intNombre" },
                    { "data": "intFechaNacimiento" },
                    { "data": "intEdad" },
                    { "data": "intSexo" },
                    { "data": "intTipoDocumento" },
                    { "data": "intNumeroDocumento" },
                    {
                        "defaultContent": '<button type="button" class="btn btn-primary btn-sm btn-editar"></button>' +
                            '<button type="button" class="btn btn-danger btn-sm btn-retirar ms-2">^__i class="fas fa-trash"></button>',
                        "orderable": false,
                        "searchable": false,
                        "width": "90px"
                    }
                ],
                "language": {
                    "url": "https://cdn.datatables.net/plug-ins/2.0.2/i18n/es-ES.json",
                }
            })
	})
    </script>
}