incorrectly formatted item amount.

After enabling free shipping. this error occured, it seems as long as the amount is 0, this will occur.
I have another free shipping mod installed, if checking out with that, the same message will occur at paypal page.
The link you have used to enter the PayPal system contains an incorrectly formatted item amount.
I'm using oc1.5.5.1. Any help is appreciated.

find a thread, http://forum.opencart.com/viewtopic.php ... 07#p517707
not sure whether it will work.
According to paypal service repy: it's symbol or comma related.
I will have a try.

This usually happens when you include a currency symbol or a comma in the price.
Can you file a ticket with us at https://www.paypal.com/mts if this is not the case?
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If i checkout with paypal, it will give error:RECEIVER EMAIL MISMATCH
http://forum.opencart.com/viewtopic.php ... 07#p517507

If i usethe mod mentioned in that thread to solve mismatch problem, it will give a different error when working with free shipping:
incorrectly formatted item amount.

If i set a value for free shipping ( i tested another free shipping mod that allows input cost values). Only after a certain amount, the " incorrectly formatted item amount." will be gone.
For example, if i set 0.1 (usd), it won't work. if i set 0.6, it won't work. until, i set 1.3, it works without error.