Assembly must be strong signed in order to be marked as a prerequisite

Today the following error occured when i tried to build my solution:

Assembly 'Mydll.dll' must be strong signed in order to be marked as a prerequisite. Strange cause i have been working on this solution for months already and never had any problems building it.

Ofcourse i tried the standard solutions in order to solve the error like:
- rebuild the entire solution
- clean the solution and rebuild
- remove mydll.dll from the references and reference it again
- check if i was pointing to the right path and the right version of the dll

None of the above made the error go away. Then i realized  i was using Mydll.dll also in Another.dll which was referenced in the solution. As it turned out, Another.dll was pointing to a different version of Mydll.dll. You can guess the rest: after referencing the right Mydll.dll in Another.dll, build it and reference the new Another.dll in my solution, the problem was gone.

I hope this helps solving this error for you too.

Regards,
Jacob