sorry, I found the error, I was calling two versions of jquery. thks

$(document).ready(function() { $('.mdb-select').materialSelect();});

<select class="mdb-select md-form colorful-select dropdown-primary" multiple searchable="Search here..">
                                    <option value="" disabled selected>Choose your country</option>
                                    <option value="1">USA</option>
                                    <option value="2">Germany</option>
                                    <option value="3">France</option>
                                    <option value="4">Poland</option>
                                    <option value="5">Japan</option>
                                </select>
                                <label>Label example</label>
                                <button class="btn-save btn btn-primary btn-sm">Save</button>