LS Nav - Apply payment to AR Invoice through POS

Scenario:
A Regular NAV invoice was done for a customer 30 days ago. Customer walks in to store to pay invoice through the POS.

Requirements:
Cashier must be able to select customer account, take the payment, pull up a list of his open AR transactions, select he invoice to pay, and apply the payment.

Setup:

http://help.lsnav.lsretail.com/Content/LS%20Retail/POS/Functionality/Commands.htm

To achieve this, the following steps were taken

• Create a "PAY AR" button that kicks off the AR process, and requests the invoice number to be paid
• Create button with command: PAYM_ACC_INV calls the payment against invoice command and uses your selection
• Parameter: Tender code (4 is Customer Account, Default function must = Customer)
• Create a "OPEN AR" button that displays all open AR
• Create button with command: LOOKUP
• Create Parameter for OPENAR_LU in the POS Lookup Card screen 
• MenuID: #LOOKUP-FI to get filters in the lookup
• Input Control ID: #LOOKUPINPUT 
• Create Data Table ID #OPENAR in the POS Data Table screen
• Table 21
• Cols:4, Rows:15, key: 6
• Selectionmode: SelectOne
• Set first column to DocumentNo
• Default search command: filter
• Set Indexes on columns to make them filterable and sortable
• Process
• User clicks PAY AR
• POS prompts for invoice
• User clicks OPEN AR
• Filter, and select invoice to be paid
• POS Prompts for amount to pay
• Enter amount to pay
• Select Tender Type
• Transaction completes, Receipt prints
• End of Day - Applications do not appear on account or against invoice until statement is posted
• After posting statement, Payments appear on customer account applied against invoice

Application data is stored in the Transaction Header.Apply to Doc. No. field
*Notes
Even if a payment has been taken for an invoice, the POS will not prevent additional payments to the same invoice.
To remove the paid invoices from the datatable list

• Modify T21 Add flowfield ToBeAppliedFromPOS to calculate sum of Transaction Header.Amount to Account matched on apply to doc no field and Customer No.
• Add field to datatable so user can see if any payments were previously applied from this pos