Problems with CSS and jQuery [closed]

I have a style defined for my select boxs and I have on change in select to execute the site of the select box, when I use style does not execute the onchange or it does not go to the site that I have in my options.

<select  class="styledselect_form_1"  onchange="location = this.value;">
    <option value="">Número de linhas</option>
    <option value="Confirmatl.php?trl=5">5</option>
    <option value="Confirmatl.php?trl=10">10</option>
    <option value="Confirmatl.php?trl=15">15</option>
    <option value="Confirmatl.php?trl=20">20</option>
    <option value="Confirmatl.php?trl=25">25</option>
    <option value="Confirmatl.php?trl=30">30</option>
</select>

The css:

.styledselect_form_1    {
    background: url(../images/forms/form_select.gif) left no-repeat;
    border: none;
    border-left: none;
    color: #393939;
    cursor: pointer;
    display: block;
    font-family: Arial;
    font-size: 12px;
    height: 24px;
    margin: 0px 0px 0px 0px;
    padding: 7px 0 0 6px;
    text-align: left;
    width: 192px;
}

the script:

<script src="js/jquery/jquery.selectbox-0.5_style_2.js" type="text/javascript"></script>
<script type="text/javascript">
$(document).ready(function() {
    $('.styledselect_form_1').selectbox({ inputClass: "styledselect_form_1" });
    $('.styledselect_form_2').selectbox({ inputClass: "styledselect_form_2" });
});
</script>