Serious Problem With Embed Fonts

Hi all,

Am creating a textbox dynamically through action script using the following line :

this.createTextField(“my_txt”, this.getNextHighestDepth(), 10, 10, 160, 120);

And i added a font symbol in the library and named it as “Lucida Sans Unicode” , and i embedded , applied text format using the following lines :

var my_fmt:TextFormat = new TextFormat();
my_fmt.font = “Lucida Sans Unicode”;
my_txt.embedFonts = true;
my_txt.text = “Hello world”;

After doing the above steps the text box “my_txt” created has the “Lucida Sans Unicode” font style , when i type in the text box also its displaying with the “Lucida Sans Unicode” font style , but the problem is when i type some maths symbols such as " ∅ , ∈ , ∉ …" its showing as box , the maths symbols are not coming . What am doing wrong ?? What should be done to display all the math symbols ??

Thanks in Advance,