Reading url and doing something with it

[madref]

I have maneged to get so far....

<script type='text/javascript'>[URL=ss]ss[/URL] function Go(){return}</script> 
<script>
// type="text/javascript" src="../Include/Menus/MenuKeuze.js">
// JavaScript Document
function GetURLParam(strParamName) 
{ var strReturn = "";
  var strHref = parent.frames['Frame_Left'].location.href;
  
  
  if ( strHref.indexOf("?") > -1 ) 
  { var strQueryString = strHref.substr(strHref.indexOf("?")).toLowerCase();
    var aQueryString = strQueryString.split("&");
    for ( var iParam = 0; iParam < aQueryString.length; iParam++ ) 
	{ if ( aQueryString[iParam].indexOf(strParamName + "=") > -1 ) 
	  { var aParam = aQueryString[iParam].split("=");
        strReturn = aParam[1];
        break;
      }
    }
  }
  return strReturn;
} 

if (GetURLParam('Taal') == 'Nederlands') 
 { if (GetURLParam('Menu') == 'Kennel') 
   { document.writeln('<script type="text/javascript" src="../Include/Menus/Menu_Hoofd_Ned.js"></script>');
   };
   if (GetURLParam('Menu') == 'FotoAlbum') 
   { document.writeln('<script type="text/javascript" src="../Include/Menus/Menu_FotoAlbum_Ned.js"></script>');
   };
 };
else if (GetURLParam('Taal') == 'Engels') 
 { document.writeln('<script type="text/javascript" src="../Include/Menus/Menu_Hoofd_Eng.js"></script>');
 }
</script>
<script type="text/javascript" src="../Include/Menus/JavaMenu_Com.js"></script>

What this does is that it calls and creates a menu.
But as you can see i want to call a different menu depending on the url thats been given.

My website has been build in frames (See picture)

The problem is that when i call the page in the left frame like : ....Frame_Left.html?Taal=Nederlands&Menu=Kennel
I everytime get the english version of the menu instead of the dutch

What am i doing wrong??