Priming tasks are better done in DirectRT. It is designed to work with timing on the millisecond level.

There are instructions and example files of a basic priming task described here in the DirectRT manual: http://www.empirisoft.com/directrt/h...rd_priming.htm

If you do not have a copy of DirectRT, you can get a free 21-day trial license to try it out. Just download it from here on the Empirisoft website: http://www.empirisoft.com/Download.aspx?index=4. When you send the 14-character D-code to service@empirisoft.com, please make sure to ask for the 21-day trial license.