Help loading dynamic text with combo?

Hi

I am trying to use the combo box component to dynamically load text into a text area on the stage.
I have set up and populated my combo box and used the on(Change) function to navigate to a url just to see if it works and it does.

I have run through the loading text dynamically tutorial on this site which is also great!

Now I would like to put the two together so when a user selects an option from the combo the contents of the texfile is displayed in the text area.
I have tried this but have fallen at the first step!

I have published the html and links to the fla here;

http://www.amdsystems.co.uk/dev/load%20text.html

Any help would be great - just a beginner so please be gentle.

many thanks for your time!

Joe