I finded the solution... it was a really naive reason!
<script type="text/javascript"
src='<%# Page.ResolveClientUrl("/Scripts/jquery-1.7.2.min.js") %>'></script>
<script type="text/javascript"
src='<%# Page.ResolveClientUrl("/Scripts/jquery.alerts.js") %>'></script>
It seems that with the charachter '~' in the relative path this script does not work... without it goes fine.