Hello Jie Lin,
I can confirm that we had this issue in the version you are using - Q1 2011. We have included a fix in our Q3 2011 release. Please upgrade with our latest available version Q3 2011 SP1 and let me know if you still experience the faulty behavior.
the Telerik team
Sharpen your .NET Ninja skills
! Attend Q1 webinar week and get a chance to win a license! Book your seat now >>