[Scripting Question] undefined method `[]' for nil:NilClass

[Kyogreblue21]

Can anybody tell me how to fix this?

Exception: NoMethodError
Message: undefined method `[]' for nil:NilClass

Backtrace:
279:UI_Pokedex_Main:28:in `species'
279:UI_Pokedex_Main:416:in `pbRefresh'
279:UI_Pokedex_Main:408:in `pbRefreshDexList'
279:UI_Pokedex_Main:293:in `pbStartScene'
279:UI_Pokedex_Main:1299:in `pbStartScreen'
278:UI_Pokedex_Menu:120:in `block (2 levels) in pbStartScreen'
082:MessageConfig:570:in `pbFadeOutIn'
278:UI_Pokedex_Menu:117:in `block in pbStartScreen'
278:UI_Pokedex_Menu:113:in `loop'
278:UI_Pokedex_Menu:113:in `pbStartScreen'