Professional :: Pass The Contents Of The Text Field To Another Text Field?

I've created a dynamic text field - mediaImportName001 (created , and populated it with the name of a file that I choose to import using a browse button (as3 and AIR).This works fine - I can import the file, and the name appears in the field.
 
I'd now like to pass the contents of the text field to another text field.  But I can't get the contents. If I try to trace the contents of the textField trace("mediaImportName"+thisNum).text     - Flash returns "undefined" (even though I'm asking it to trace after the field has been populated).
 
I use the following code to check that the field really is there and named correctly (the code returns the children):
 
for (var i:uint = 0; i < this.numChildren; i++){    trace (this.getChildAt(i).name + ' type:' + typeof (this.getChildAt(i))+ ' ' + this.getChildAt(i));}
 
it returns:
 
instance370     type:object    [object Shape]mediaImportName001     type:object    [object TextField]mediaFiletype001     type:object    [object TextField]
 
How do I get Flash to give me the text in mediaImportName001?  
 
It's bizarre - this.getChildAt(i).name
 
from above gives me...
 
mediaImportName001     ,
 
yet
trace (["mediaImportName"+thisNum].name); 
 
returns undefined (thisNum represents an increment I use to name multiple clips and text fields, and in this case trace(thisNum); returns 001)