tab stop

Hello, I make new text frame in illustrator CS document.
It's frame mast have certains propertise, including same
1)tab position, which in illustrators menu in window/type/tabs
2)leading.
I try do it so:

1)
set tab stops of paragraphs of text of MyTextframe to {center,10,2}

(in illustrator 10 scripting guide
Property: R/O Value type: What it is:
alignment unknown/left/center/
right/decimal
The alignment of the tab stop.
decimal character string The character to use for
decimal tab stops.
position real The position of the tab stop.)
But when I have error.
Question 1: How can I set tab stops propertise?

2) It have several variant

set leading of text of Mytextframe to 8.9
or
set leading of paragraphs of Mytextframe to 8.9
or
set leading of characters of Mytextframe to 8.9

All of them don't have error, bat and leading in MyTextFrame don't changes,
and = 7.8
Question 2: How can I set leading propertise?

Please halp!