The types from namespaces
are defined in assembly Telerik.OpenAccess.35.Extensions.
Adding a reference to that assembly should fix the problem.
Please bear in mind that the assembly Telerik.OpenAccess.40.Extensions.dll
an upgrade nor a replacement for the assembly Telerik.OpenAccess.35.Extensions.
These assemblies are very different from each other.
article explains in detail which assemblies are needed in order to use OpenAccess ORM.
This should be also the answer to these support threads as well:
I hope that helps. If you still experience any difficulties compiling the project get back to us for assistance.
OpenAccess ORM Q2 2013 brings you a more powerful code generation and a unique Bulk Operations support with LINQ syntax. Check out the list of new functionality and improvements shipped with this release.