How to link from a selection list to a complete new php site

How to link from a selection list to a complete new php site

Hi everybody.

I'm new to this here, so please be patient with me. I have a problem with a link to a new php file.
Under the following URL you can see where my problem is:
In the upper left corner is a button with the label "Fondsfinder". If you click on it a selection list pops up, kind of a dialog. If you choose the first entry that is named "HANSA D&P" the file "fondsdetails.php?fondsId=12" should be opened and some information about this fund should be appear. But sometimes it shows the right site for about a second or less and switches back to the homepage where I just came from. And sometimes it shows the right site, but it doesn't work a second time when you go back in the history in your browser. It's totally weird... I tried every possible combination, but nothing worked.
If you choose any other fund on the selection list it should only appear the sentence "No information about this fund found" (in german).
This is the javascript out of the first file I tried at least to work:
$("#select-menu-0").bind ("change", function (event) {
      alert('Value changed to ' + $(this).attr('value'));
      var fondsId = $(this).attr('value');
      //$.mobile.loadPage ("hansadp.html");
      //$('#home').bind('pageshow', function() {
      $.mobile.changePage ("fondsdetails.php?fondsId="+fondsId, {
      type: "get"
      // data: $("form#fondsselector").serialize() });

In the second file is no javascript.

I really hope somebody can help me and make this thing run.

Thx a lot