Help regarding the code hint in flash cs5

Hi i’m a new to AS 3.0 need a small help
i’m using flash cs5 processional in this my CODE HINT does’nt work properly
it pops out automatically when i m using the**[COLOR=#ff0000] : (colon)[/COLOR]** key
but when i press**[COLOR=#ff0000] .(dot)[/COLOR]** it does not pops out
can any one please help me if any particular setting has to be made for this