Searchbutton werkt niet op iPad, iPhone, HTC

<!--BEGIN Search Box -- onkeyup="suggestion(event)">
<form action="/about-joomla.html?page=shop.browse" method="post">

    <!--<p><label for="keyword">Zoeken</label></p>-->
    <div class="search id="search-product">
        <input name="keyword" type="text" size="50" title="Zoeken" class="inputbox" id="keyword" value="Titel, Auteur, ISBN, Trefwoord..."
            onclick="javascript:if(this.value == 'Titel, Auteur, ISBN, Trefwoord...')this.value = '';"
        onblur="javascript:if(this.value=='')this.value = 'Titel, Auteur, ISBN, Trefwoord...';" />
        <!--<input class="button" type="submit" name="Search" value="Zoeken" />-->
        <input class="button" type="submit" name="Search" value="Zoeken" id="search-button" />
    </div>
</form>
<!-- End Search Box -->

<!--BEGIN Search Box -- onkeyup="suggestion(event)">
<form action="/about-joomla.html?page=shop.browse" method="post">
 
    <!--<p><label for="keyword">Zoeken</label></p>-->
    <div class="search id="search-product">
        <input name="keyword" type="text" size="50" title="Zoeken" class="inputbox" id="keyword" value="Titel, Auteur, ISBN, Trefwoord..."
            onclick="javascript:if(this.value == 'Titel, Auteur, ISBN, Trefwoord...')this.value = '';"
        onblur="javascript:if(this.value=='')this.value = 'Titel, Auteur, ISBN, Trefwoord...';" />
        <!--<input class="button" type="submit" name="Search" value="Zoeken" />-->
        <input class="button" type="submit" name="Search" value="Zoeken" id="search-button" />
    </div>
</form>
<!-- End Search Box -->

<!--BEGIN Search Box -- onkeyup="suggestion(event)"-->
<form ...>

<!--BEGIN Search Box -- onkeyup="suggestion(event)"-->
<form ...>