Ebay free domestic shipping error

I am submitting 4 domestic shipping methods to Ebay using the C# dll. 3 of them are free and one is not. I am getting this error, which doesn't appear in the documentation (or I can't find it)

Warning: Free postage is only applicable for the first postage service. Free postage will not be applied for this service. You must enter a postage cost.

I tried submitting the free delivery services first, but it keeps telling me this.

Solution

The issue here was actually two things:

You can just submit one shipping service as free.
Free shipping service must be the first one in the list.

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