A/P Batch Posting problem

I have a user who is having a problem getting a A/P batch (session) to 
process.

When I look at the session inquiry, the status shows as 'F' (finished) as 
opposed to 'P' (processed).  Also, when looking at the Invoice Inquiry, of 
the 14 known invoices to be in the batch, only the first invoice in the 
group and the last five invoices in the group show as posted.  The other 
invoices don't show up.

What do I need to do to post the other invoices in the batch and get the 
batch to a "processed" status?

Thanks in advance.