AttachMovie and dynamic text with variable

Ok, I’m stuck on a very simple problem.
I want to access a dynamic text field inside a movie clip, that I created using a variable as a name.

I have a movie clip whose instance name is cc_mc and a dynamic text field inside it, called textF.

THIS works:

var mname= "cc_mc"
this.attachMovie("cc", "cc_mc", this.getNextHighestDepth()); 
this.cc_mc.textF.text = "EEEEEEEEEEEEEEEEEEEEEEK"; 

(not the first line is redundant here)

THIS does not work: I cannot change the text field content.

var mname= "cc_mc"
this.attachMovie("cc", "cc_mc", this.getNextHighestDepth()); 
this.mname.textF.text = "EEEEEEEEEEEEEEEEEEEEEEK"; 

THIS
does not work either:

var mname= "cc_mc"
this.attachMovie("cc", "cc_mc", this.getNextHighestDepth()); 
this["mname"].textF.text = "EEEEEEEEEEEEEEEEEEEEEEK"; 

What is wrong with it?
Any help is greatly appreciated.

Stefano