Sometimes when you pin an application (this happened in 6 on occasion) the command to launch may not always be present - you can create your own custom launcher on the panel but you need to know the commands which means you need to know the exact command that launches the application from the menu.
1. Go to the Menu and 'select' (left-click) an app then right-click it for 'Properties' - you will see an entry in the 'command' box - these always end in '%U' (for User)
2. Copy this command into the 'command' box in your custom launcher - it should pick up the applications icon based on the command.