Thanks, i was able to see the issue. I did a test with eCart and i was not able to reproduce this issue, but we should be able to fix it.
in your WA_eCart folder, please open a file that is name "your ecart name_PHP.php", i believe in your case it could be called "racechip_PHP.php" and in the file, look for this line of code:
then change the 7th parameter to be a 0. So you are going to see something like this:
new eCart1_Definition("eCart1", 0, "£", "", true, 2, 0, "oz", true, 2, 1, 0);
the 7th parameter in this case is a 0.
Let me know if you have any questions.