border-radius work fine in ie6,7 but cannot work in ie8. anyone aware of this?

All features work just fine in IE8. But sometimes there are other factors which cause problems. You'll have to give more information, like:

* When you say it "cannot work in IE8", what exactly do you see? Do your corners stay square, does the background/border disappear entirely, or something else?
* Can you post a code snippet demonstrating your problem?

Also, please make sure you've read the Known Issues documentation page to make sure you're not running into any of the frequently encountered problems: http://css3pie.com/documentation/known-issues/ -- most often people run into the first section regarding z-index.

the background-color and border disappeared all together on ie8 . but work fine in ie6,7. it is just a simple div with border, i do not use position:static.

Again, you have to provide more information for us to help you. PIE works just fine in IE8 for many users, so it's likely there's something in your setup which is causing the issue.

When you say you are not using position:static, does that mean that you are using position:relative?

problem solved. thanks @Jason