You can see the invoice for every transaction by clicking the PAID link under the STATUS tab. The link will take you directly to the invoice.Every transaction has TWO LINE ENTRIES. 

In example 1, a partner has billed his client for website maintenance 107 (Individual Website Packages) and the corresponding invoice can be seen by clicking the paid tab. 

In ID 108 the website ID corresponding to this transaction.

Here is how to see your invoice:

Step 1: Log in to the CRM.
Step 2: Click on partner administrator tab (A).
Step 3: Click on the Transactions tab (B). 
Step 4: Click the paid link (1 in orange)