embed the font of your dynamic textfield.
I can't understand what happening your textbox. You can send your code
You might want to unlearn some of what you are learning here.
Using the var property of a text box is likely to cause you problems somewhere down the road. That was how you got text into textboxes back inf Flash 5 or so. When Flash 6 came out it was much better form to use the text property of the textfield and assign the contents that way.
Also if you are just learning Actionscript/Flash and you have no overwhelming reason to learn AS2 then it would probably be better to start learning AS3 right off the bat. That way you won't have to unlearn all the "bad" AS2 things you learned and you will have a future going forward with AS3.
And, oh yeah, what kglad said about embedding fonts.