I believe the rule for joining any subject areas are

• Use common dimension fields
• Include a measure from both subject areas
• You don't have to use these in any of your tables or charts just in the criteria

I think the issue your probably dealing with are the AP related transactions.

They are not accounted in projects, so if you are looking for the accounting on invoices from project costing / GL the do not get accounted from projects to GL. It's AP to GL.

I have had some luck using project costing and subledger journals area to get the things like raw cost / raw cost clearing / burden cost / burden cost and using accounting class code in subledger journals to view the class, debit/credits along with concatenated segments posted to.

For invoices I've used a combination of invoice transactions subject area mixed with subledger journals and project costing to get the invoice postings.

You may need a complex query to combine both side that post from projects to GL along with the AP transactions posting directly to GL. (If there is burden calculated against invoice that will get picked up from project postings since that goes from projects to GL).

Only issue I've really had is when there is a payment discount back to the project, sometimes I'm unable to find the project # related to the discount on GL side specific, but you may have something like a supporting reference to do so.

Hope this helps...also suggest looking a the pre defined dashboard, keeping in mind same issue there is will only show costs originating in projects posting to GL, but not invoice posting.

Project cost account reconciliation (maybe copy the queries and edit to see the design)