Nightmare old flash 4 code

Is doing my head in! I’ve got this really great code that combines duplicate mc’s based on dynamic input that darg left and right, but the interaction in between is flash 4 and I’m have problems with all these /: things everywhere and it’s making the bits of MX that I want to use fail because it’s outputting as a flash 4 document.

Why when I’m one step inside a movie clip on the timeline, would /:tmi not be the same as _root.tmi?

Any pointers appreciated.