Slide show navigation with arrow keys

I’m building an interface for a co-worker who makes presentations. I’m using an XML-based system that pulls jpegs and text from an external directory.

Everything’s going fine, except he would like to be able to move forward and backward using the left and right arrow keys. I’m using code that has forward and back buttons with code on the main timeline but I’d like to change that to the arrow keys. However I keep getting syntax error messages.

Any help will be appreciated.