Thank you for your reply.
I am getting a warnings message: "Found conflicts between different versions of the same dependent assembly."
And I am unable to do a release. Since it is not Ajax Toolkit, I scanned through the list of assemblies in my project again.
I updated the ref: "System.Web.DataVisualization" from .Net 2.0.50727 to .Net 4.0 which resolved the warning and compiled fine.
But when I open dynamic dashboard, the following error appears in each of the widgets,
(0): error CS1705: Assembly '*****, Version=6.4.4387.21941, Culture=neutral, PublicKeyToken=8c5a4204adb4e962' uses 'System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' which has a higher version than referenced assembly 'System.Web.DataVisualization, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'