新手简单的PHP分页有关问题，但是不知道为什么不分页

新手简单的PHP分页问题，但是不知道为什么不分页？

PHP code

<!--

Code highlighting produced by Actipro CodeHighlighter (freeware)
http://www.CodeHighlighter.com/

-->

function pager($rows,$page_size){ 
global $page,$select_from,$select_limit,$pagenav; 
$page_count = ceil($rows/$page_size); 
if($page = $page_count) $page = $page_count; 
$select_limit = $page_size; 
$select_from = ($page - 1) * $page_size.','; 
$pre_page = ($page == 1)? 1 : $page - 1; 
$next_page= ($page == $page_count)? $page_count : $page + 1 ; 
$pagenav .= "第 $page/$page_count 页 共 $rows 条记录 "; 
$pagenav .= "<a href="?page=1">首页</a> "; 
$pagenav .= "<a href="?page=%24pre_page">前一页</a> "; 
$pagenav .= "<a href="?page=%24next_page">后一页</a> "; 
$pagenav .= "<a href="?page=%24page_count">末页</a>"; 
$pagenav.="　跳到<select name="topage" size="1" onchange='window.location=\"?page=\"+this.value'>\n"; 
for($i=1;$i$i\n"; 
else $pagenav.="<option value="$i">$i</option>\n"; 
} 
} 

 include("conn.php");

///////////////////////////// 利用pager函数计算出 $select_from 从哪条记录开始检索、$pagenav 输出分页导航 
$rows = mysql_num_rows(mysql_query("select * from manager")); 
echo $rows;
pager($rows,2); 
$sql = "select * from manager limit $select_from $select_limit"; 
echo $sql;
$rst = mysql_query($sql); 

while($row=mysql_fetch_array($rst)){
?>
        <tr bgcolor="#FFFFFF" onmouseover="javascript:this.bgColor='#D9FA9C'" onmouseout="javascript:this.bgColor='#FFFFFF'" style="CurSoR:hand;">
          <td align="center"><input type="checkbox" name="SelectItem" value=""></td>
          <td align="left">=$row[chinaname]?></td>
          <td align="left">=$row[username]?></td>
          <td align="left">=$row[Purview]?></td>
          <td align="left">=$row[password]?></td>
          <td align="center">=$row[Tel]?></td>
          <td align="center">=$row[FAX]?></td>
          <td align="center">=$row[Mobile]?></td>
          <td align="center">
            if ($row[sfxs]==0){
             echo "显示";
            }else{
             echo "隐藏";
            } 
          ?></td>
          <td align="center">
            if ($row[sfjy]==0){
             echo "禁用";
            }else{
             echo "启用";
            } 
          ?></td>
          <td>=$row[Adddate]?></td>
        </tr>
  
  }
  echo $pagenav;
  ?>


</select>

具体页数都算出来了，就是点击下一页不能进行翻页，很郁闷

------解决方案--------------------
pager 函数中要用到的变量 $page 在哪里赋值的？