Two questions:
1. Is it simple mate of two locationally unconstrained features, like a cylinder and a hole, or there are locational tolerances that position these features to other features which also mate together in the assembly?
2. If this is ISO, your fit may always work only if the Envelope Principle is defined (circled E next to dimension). Is it there? Without it the straightness of the features measured lengthwise is not controlled at all, so despite both features being in tolerance (they satisfy two-point measurements) they may not match due to a bow or any other form error of similar nature.
Those questions apply two both of your threads.