When a sales invoice batch won't post in Dynamics GP (Great Plains), the first step is to identify the problem. Historically, Dynamics GP has not been good at flashing to the user an error message when it doesn't post. Thus, the user has a hard time understanding what the problem is. They don't know where to begin.
There are 2 ways to discover the source of the problem:
1) Print the batch edit report.
Go to Transactions > Sales > Sales Batches. Select the batch that won't post. Then click on the printer icon in the corner of this screen. This will print a report which will often have on it an error message for the transaction(s) that have a problem.
OR
2) Try posting the transaction(s) individually without using a batch.
Pull up the transaction by going to Transactions > Sales > Sales Transaction Entry and navigating to the transaction that won't post. Then remove the transaction from the batch (just put your mouse on the batch id field and hit the delete key). Then try to post it by clicking on the post button in this same screen (or in later versions of Dynamics GP, click on Actions then select post). By posting it outside of a batch, an error message window will come up with a better description of the problem.
NOTE: Sometimes, you cannot do any troubleshooting because the batch becomes "corrupt" and you cannot edit it or even pull up the batch as described in step 1. If so, you may need to go to the Batch Recovery window (on the main menu, go to Tools > Routines > Batch Recovery) to restore the batch to the point of being able to edit it.