Hello pv Upendran,
There are several possible causes of this type of error - one might be that you do not have the latest Windows Installer package which can be found here
. Could you please install this package and try to install our suite?
You can also run our suite installer in verbose mode which might gather valuable information about the exact cause of the problem. If possible could you run our installer using the command prompt by executing the following command : RadControls_for_Silverlight_2009_2_812_TRIAL.msi /L*V log.txt where log.txt is the name of the log file and RadControls_for_Silverlight_2009_2_812_TRIAL is the setup file. We will appreciate it if you could send us this file.
Hope this helps and thank you for your patience and understanding.
the Telerik team