Did you try to visualize it under UV light?

If you use TLC with UV 254 nm indicator, you should see a dark spot where the compound is putted, over a green flurescent olayer of the TLC. I am pretty sure that perilene derivatives must absorb UV radiation.

As alternative you can use a reagent to color the TLC, such as suphuric acid (2M and then heat the TLC) or Phosphomolodbic acid (10% w/w in EtOH, and then heat until you can see the stain). Just put the TLC inside sthe reagent solution then heat at no more than 150 °C.

Hi, please search in the Camag TLC data base; I found 21 if I insert key word perylene, and 5 for diimide. kind regards

http://www.camag.com/en/tlc_hptlc/customer_magazine_cbs/ccbs_database.cfm?method=query

Perylene diimide derivatives should be coloured in red (some are black) by themselves so they should be visibile in TLCs without treatment with reactive or UV. Depending on the substituents some derivatives have little solubility due to the tendency to stacking. May be this is the problem.