Strange results on Simulink

Hi,

I'm modeling a Permanent Magnet Synchronous Machine on Simulink and I have a profile which gives me good results (speed is OK, ...). But I have some problems I don't understand... For example, when I copy/paste a block (Subsystem) from another version on my last version BUT I don't link this block to anything else , the results are bad (speed becomes negative, ...).

Another example : I have a subsystem not linked in my model and the result are OK. I link the inputs but not the outputs of this block. I don't change anything in my system because I don't use this block but the results are bad.

I don't know why Simulink is doing that, so if you have some explanations ...

Thank you.