I am not familiar with this type of OFDM. You have 60 LEDs all being modulated by the same signal operating at the same optical frequency. Can you explain your desired system in a little more detail? I would suggest starting with a simpler design maybe one LED and see if you can get the hang of it.
Also there is a quick fix you can do by setting proper settings in a Decision component for the old OFDM components. Follow the example at:
Regards