how to upload above 1MB file using PHP

[vijy]

hai,
I am trying to upload a file which is 3.4MB(gif file).according to my code i am storing the file in folder named advertisment.If i upload above 1.5MB ,the file get uploaded in the database,but not in the folder.if i did less than that..the file is available..
i have also cHanged the php.ini file..upload_max_file=8MB,I have used enctype="multipart/form-data"
this is my code..

<?
if(isset($_POST['submit']))
{
$ext=substr($_FILES["photo"]["name"],-4);
$category=$_POST['category'];
$date=date('Y-m-d');
$sql_check="select * from conadv where category='$category'";
$query_check=mysql_query($sql_check) or die(mysql_error());
$num=mysql_num_rows($query_check);
if($num==0)
{
$sql_advertisment="insert into conadv(photo,category,date) values('$ext','$category','$date')";
$query_advertisment=mysql_query($sql_advertisment) or die(mysql_error());
$id=mysql_insert_id();
$filename="conadv".$category.$id.$ext;
$uploadFile = "../advertisment/".$filename;
if (copy($_FILES["photo"]["tmp_name"], $uploadFile))
{
//header("loaction:viewmain.php");
}
}
else
{
$error="Alredy Exists";
}

}
?>

kindly help me friends...try to solve this pbm