Millisecond Forums

I am searching for a method where the experimenter can adjust the times in which stimulus are displayed within a trial. 

I have been unsuccessful in getting the following fragment to work:
http://www.millisecond.com/support/docs/v4/html/language/properties/stimulustimes.htm

 Say for the example below I want to now want to alter the presentation time of stimulus textb?

<trial mytrial>
/stimulustimes=[0=texta; 500=textb]
/ validresponse=("a")
</trial>

<text texta>
/items = ("texta")
</text>

<text textb>
/items = ("textb")
/position = (25,70)
</text>