Paging Help

hello frnds this is my website http://www.sms2friends.co.cc...in my website there are some catgories on left side..when i click on first category the content of annivesery sms categry display on middle column with paging...but my paging function is not working properly...i want 5 joke per page.. 5 joke are disply and paging script also running but whn i clik on seconday page of my paging script..its not working..
please chk my code and help me

<table id="table_main">
<tr>
<td width="17%" valign="top">
<table id="side">
<tr><td><?php
mysql_connect("localhost","root","vertrigo");
mysql_select_db("sms");
$result = mysql_query("SELECT * FROM categories");
while($row=mysql_fetch_array($result))
{
echo "<a href='index.php?app=1'>".$row['anniversary']."</a>";
echo "<br />";
echo "<a href='index.php?app=2'>".$row['birthday']."</a>";
echo "<br />";
}
?></td></tr></table></td>
<td width="66%" valign="top"><table id="side">
<tr>
<td><?php
switch($_GET['app'])
{
case 1:
$page = $_GET['page']; // Set the Page From the Get Parameter
if(!isset($page))
{
$page = 1; // If Get Parameter not set then make $page to 1!
}
$posts = 5; // How many Posts on one Page
$start = $page * $posts - $posts; // Calculate the start Page!
$result = mysql_query("SELECT id FROM anni");
$how_much = mysql_num_rows($result);
$how_much = $how_much / $posts; // How many Pages altogether
$result =mysql_query("SELECT * FROM anni LIMIT $start, $posts"); // Select the fields from
while($row = mysql_fetch_array($result))
{
echo $row['msg'];
echo "<br>";
echo $row['date']." ".$row['name'];
echo "<hr>";
}
break;

case 2:
$result = mysql_query("SELECT * FROM birthday");
while($row=mysql_fetch_array($result))
{
echo $row['msg'];
echo "<br>";
echo $row['date']." ".$row['name'];
echo "<hr />";
}
break;

default:

}

?></td>
</tr>
<tr>
<td><?php
for($a=0; $a < $how_much; $a++) // The paging function
{
$b = $a + 1;
if($page == $b)
{
echo "<b><u>$b</u></b>"; // If the selected Page the same as the current Page then it make the number bold!
}
else
{
echo " <a style=\"color:000000\" href=\"index.php?page=$b\">$b</a>&nbsp;"; // The Links for the Pages
}
}
?></td>
<td></td>
</tr>
</table>
</td>
<td width="17%" valign="top"><table id="side">
<tr><td>asdfasd</td></tr></table></td>
</tr></table>


PLEASE CHK THE LINKING OF PAGING THERE IS A PROBLEM.....IF CHANGE LINKING THIS echo " <a style=\"color:000000\" href=\"index.php?page=$b\">$b</a>&nbsp;"; TO
<a style=\"color:000000\" href=\"index.php?app=$_GET['app']&page=$b\">$b</a>
I AM GETTING ERROR

 

I will recommend you check some pagination scripts at http://www.1afm.net/scripts/indexf.php
See under the Pagination category.
Hope that helps you.
Mayz