Sorry to hear that you are still struggling with this.
I don't know what version of GP you are using but I see I gave you some old security steps in my previous post. Sorry about that!
Try these instead:
1.On the Microsoft Dynamics GP menu, point to Tools, point to Setup, point to System, and then click Alternate/Modified Forms and Reports.
2.In the ID box, click the ID for the alternate form or for the alternate report.
Note The default ID is "DEFAULTUSER."
3.In the Product list, click Project Accounting.
4.In the Type list, click Windows.
5.Expand the Sales folder.
6.Expand each folder.
7.Click Project Accounting for each folder.
8.Click Save.
9.On the Microsoft Dynamics GP menu, point to Tools, point to Setup, point to System, and then click User Security.
10.In the User box, click a user ID.
11.In the Company field, select the company.
12.In the Alternate/Modified Forms and Reports ID field, add the ID that you clicked in Step 2. This grants the user ID access to the alternate window so they can get to the Apply Projects window.
13.Click Save.
Once you have done that then reapply the invoice and cash receipt and you should see the Project Accounting information populated.
If that doesn't fix it, then are other cash receipts applying correctly to other invoices? If so, then I suspect there is something wrong with the billing invoice itself. You will want to check out Resolutions 2 and 3 from this KB article for more information.
support.microsoft.com/.../2278974
Let us know if you have any more questions.
Pam