URL variable/value doesn't get picked up by php

I have this code to create a new OrdID if no value for this variable exists:

If ($OrdID=="")
{
$con = mysql_connect("localhost","xxx","xxx");
mysql_select_db("xxx_Order", $con);
$query=mysql_query("Select Max(OrdID) FROM `Order`");
while($row=mysql_fetch_array($query))
{
$OrdID= $row[0] + 1;
}
$sql = "INSERT INTO `xxx_Order`.`Order` (`OrdID`) VALUES ($OrdID);"; 
if (!mysql_query($sql,$con))
  {
  die('Error: ' . mysql_error());
  }
mysql_close($con);
}

Of course before the above code I have(and I tried to place below code first line of my php file, in the head section and in the body section and also tried $_GET instead of $_REQUEST:

$OrdID=$_REQUEST["OrdID"];

But when I copy/paste following link in the browser the variable/value doesn't get picked up and above code creates a new OrdID: example.com/test.htm?OrdID=304819

What am I missing? Thanks

Tried $_GET instead of $_REQUEST. Placed code at different sections

Update: Actually I think I know the problem...its my htaccess redirect of:

RewriteRule link--(.*)\--(.*)\--(.*)\--(.*)\--(.*)\.htm$ example.php?Vendor=$1&Maincategory=$2&Source=$3&Pos=$4&Search=$5

Why I think it is the above redirect is because no matter what I add at the end of example.com/test.htm it will always redirect to:

example.php?Vendor=$1&Maincategory=$2&Source=$3&Pos=$4&Search=$5

Fully understand if this gets downvoted as a very poor solution.

I just can't work out how to pass on the %{QUERY_STRING} so my poor but working solution is: Added another redirect:

RewriteRule link--(.*)\--(.*)\--(.*)\--(.*)\--(.*)\--(.*)\--(.*)\.htm$ example.php?Vendor=$1&Maincategory=$2&Source=$3&Pos=$4&Search=$5&OrdID=$6&UserID=$7

Thanks