The tag 'GeometryCloneConverter' does not exist in XML namespace

I still having same issue after all effort by using latest version as well as  Old version dll. uninstall old version, install new version and using telerik upgrade menu, no help either. no discussion in your forum to help this. i need to deploy the demo next week but stuck with this unknown error.

your steps delete, create is our common practice, so pls provide more concrete answers.