[mikalou]

I don't think you can do what you want in the markup feature under shipping charges. I believe you'd need to modify the code in /include/func.php. Use a conditional statement to check the cart total and if that total is below a specific dollar amount then you'd add the extra handling fee to the total.

Try this...
In function: func_calculate_single
After this code: $total = $discounted_subtotal + $shipping_cost + $total_tax;

Add:

if ($total < 100)
  $total = $total + 25

Change the dollar amounts (100 and 25) to whatever you need.

If you need the extra handling fee to show up as a line item in the cart totals for the shopping cart, invoices, order history and confirmation emails, then you'd need to do extra programming similar to my original example.

I think I've seen other posts discussing what you want to do so try doing a search. There may be a better way than what I'm suggesting.