Amitoj,
Are you stating that you downloaded the later SMP 3.0 SDK Agentry tool kit and you are using the Agentry-V5.jar in that to customized your application or are you using the same code you implemented back in SMP 2.3 ?
The same link you gave above has the main documentation on how to implement most of this Agentry feature but you have to make sure you are using the one available in the SMP 3.0 SDK SPx files. In the same link, one of those link will have a description on how to use or create your new Agentry tool set.
I am speculating either you are using files that are not part of the released SDK and you may be using older ones that may not be compatible with SMP 3.0 (Where did you get the Agentry-V5.jar or in theory most of the application feature is in SMP 3.0 unless you are doing custom dev that you may require the tool kit).
Regards,
Mark Pe
SAP Platinum Support Engineer