J2ME LWUIT lib, textfield password not showing last character

Question

I'm a little bit new to J2ME ... I'm using LWUIT as my UI library.

My question is: I want to display a password TextField that accepts numbers only (I succeeded), but the problem is, when making it accepts numbers only, the last character is not showing however the last character appears when I remove the numeric constraint!!!

i.e.: password TextField shows last character like: *****m

here is the creation of the TextField, no complexity

tf = new TextField();
tf.setSize(new Dimension(100, 20));
tf.setMaxSize(20);
tf.setConstraint(TextField.PASSWORD);
tf.setInputMode("123");

Form form = new Form();
form.setTitle("Title");
form.addComponent(tf);
form.show;

Thanks in advance, Arshi