Hi Jim,
On these transactions that won't transfer, I would check to see if all the reqiired fields are filled in.
I have seen it before where a required field won't be filled in by eConnect but because the transfer process needs it it causes the problem you are seeing.
I would also verify that the inventory is allocated/fulfilled as you expect.
When I have had these problems before I usually go to the GP screen itself and open/close all the windows and make sure it saves ok and have often found the problem that way.
If that does not work, I would suggest selecting a good order and bad order from teh database into Excel and compare the fields to see what might be missing.
Another way to troubleshoot this is to try and import one of your transactions as an invoice instead of an order and see if it gives you an error in eConnect or a posting error in the Batch Edit Report for the invoice.
Usually it comes down to some field(s) not being filled in and eConnect not throwing an error.
Let me know if I can get you any other info.
Thanks,
Adam