use zero amount as trial

configure_privat_mail.tpl

@@ -123,7 +123,7 @@
                                 </div>
                             </div>
                         {else}
-                            <div class="field-container" display="none">
+                            <div class="field-container" style="display: none;">
                                 <div class="form-group">
                                     <label for="inputBillingcycle">{$LANG.cartchoosecycle}</label><br />
                                     <select name="billingcycle" id="inputBillingcycle" class="form-control" onchange="{if $configurableoptions}updateConfigurableOptions({$i}, this.value);{else}recalctotals();{/if}">