Are some m42 to M 4/3 mounts different?

[kknox]

I bought an M42 to M4/3 mount for some of my lens. If I use the Pentax screw mont lens they all focus fine. If I use the CZ Jena Tessar from the 50's m42 mount the lens will not even focus past a short distance. Do I need a different m42 mount for that lens?