Problem with Paypal standard and shipping amounts

Hi,

I have recently set up PayPal standard on a website but I am having trouble with the shipping side of things.

While on the opencart checkout page, the shipping amount is shown correctly, but then when the user is transferred to PayPal, the amount jumps from £5.00 to £10.00 for some reason.

Does anyone know what the problem might be and how I can fix it?

Thanks for any help

Forgot to mention the Opencart version number is 1.4.9.3 if that makes any difference

Also, this only happens if one item is in the cart - if the cart contains more than one item then PayPal recieves the correct shipping cost.

All paypal issues were fixed in 1.4.9.5.
You can get the patched version of paypal standard for 1.4.9.3 here:
http://forum.opencart.com/viewtopic.php?f=2&t=17855