If you are using the oldest software here is a work around; otherwise follow this link to download the latest version.
You will need a version of Google Earth (Desktop version) installed on your computer.
Step 1 - Open your existing playlist under GPS Builder.
Step 2 - Choose Export to Google Earth and Save As .KML
Step 3 - Launch Google Earth.
Step 4 - Click on File and Choose Open .KML (Browse your computer until you find your previously saved .KML file)
Step 5 - Add your new coordinate by using Pin Drop and rename it.
Step 6 - All your coordinates should be under Temporary Places Tree located at the left side of your screen. Once you are done Highlight Temporary Places.
Step 7 - Save as your new .KML
Step 8 - Under GPS Builder Click on New and choose Import from Google Earth.
Step 9 - Add your functions to your new points (ex. Play, etc) and save your file.
Step 10- Enjoy!
We are hoping this quick guide will help you to resolve your issue.