hi, I have downloaded the demo version of sapphire plugins for ds 8.4 on 64 bits directli of genarts page, when i try  to use it nad render the effect therender its black any one knows what is happening? 

Yep, it means that you don't have the license  installed. After a  while, that Demo version times out.

 but the license says that xpire on 29 may this is my problem i wnna know if are there any problem whit this software, my system config its an hp 8400 whit 4gb ram, dual quad core 2,8 mh and nitris box

Have you EVER been able to see these demo plugs? Gen Arts' demo software have been known to time out early.

Best bet is to ask on their site. They are great about customer support.

 When the free trial expires, the effects continue to work with a Sapphire watermark superimposed on the frame.  Do you have a permanent license?  If so, something is malfunctioning and I would suggest you contact Liz (liz@genarts.com) or Todd (todd@genarts.com).

Actually Larry, when  the demo expires, the plugs go black. I've had that happen often.

 I guess they've changed that since the version I have installed.