Error Message, Cannot Create an Invoice

I am getting this message:  This matter has an Invoiced but Unapplied Payment.

The reason an invoice cannot be created is that a PMT, RAP, TAP, CR or WO transaction has been through an invoicing cycle but has not yet been applied and posted. To remedy this, open AR Manager and access ACTION, Payment Application Posting. Locate and double click on the offending transaction to open it in the AR Entry screen. Apply and post the transaction. You may now go back and generate an invoice.