Your "example code" doesn't make sense. You show $LEDcfg being a string, then you call a method on it expecting to extract a particular value out of it. Something's missing. Perhaps whatever configuration module you're using doesn't work the way you're attempting to use it.

Absent the actual code you're using no one's really going to be able to do more than vaguely guess what's actually going wrong. Step back, fire up the debugger (run with perl -d YOURPROGRAM; see perldebug) and/or embed some debugging prints and make sure that $ApID is what you expect (and/or that the putative $LEDcfg instance works the way you think).