ObjectDataSource Wizard will list all available types that can be used with the ObjectDataSource component from the current project and from all other referenced projects which includes all public, non-abstract, non-generic
classes and structures organized in a hierarchical manner and grouped by namespace.
If the desired type/namespace does not appear in the list, make sure the current project is built and all necessary project references are added. Have in mind that Visual Studio is a 32-bit application, so the designer is restricted to x86 mode even on x64 platforms, which prevents the ObjectDataSource Wizard from discovering any types from x64 assemblies. The solution is to use different platform configurations: for "Debug" builds it is best to use "Any CPU", while for "Release" builds you can use "x64" instead.
A similar issue has been discussed in our forums and you may find useful the suggested solutions in the forum thread: Custom Type/Class unavailable in Configure Object Data Source Wizard
I would also suggest you to check the ObjectDataSource component troubleshooting
help article to avoid issues when previewing reports that use ObjectDataSource.
I hope the provided information would help resolving the issue.
If the problem persists, I would appreciate it if you sent us a runnable sample project that experiences the issue, so that we could investigate it and provide you more specific advises.
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