Here is the way to set up and select a second price (e.g. trade instead of retail) when creating an invoice:

1. Set up your system to enable the use of multiple pricing:

File/system options/ + Professional Tag
Enable multiple retail pricing level must be checked
Set the Total price level in the menu to the different price levels you want to use ie 2 (1 for retail and 1 for trade)
hit OK

2. When adding a new product or changing an existing one, set the available price levels, e.g. Retail 1: 200, Retail 2: 100 (for 2 available price levels...)

3. To be able to use the 2nd retail price for trade customers you need to create a "generic" trade account:

Click on Cust
Click on the Customer button
Select Insert Customer
Enter the code you want to use in the Last/Company field e.g. Trade
Select the price level you want to use for the trade customers in the price level drop down menu, e.g. 2 (this refers to the 2nd price you created)

4. To do a sale to a trade customer:

Click on invoice
Enter Trade (or the code you selected)
scan the product barcode
the price will automatically be the trade price.