Thread Subject: Matlab outputing wrong transfer function?

I was testing Simulink and I placed a 'du/dt' block between and input and output block, then ran

[A,B,C,D] = linmod('system')
[num, den] = ss2tf(A,B,C,D)

this returns the transfer function as 0/1. Shouldn't it be s/1 ?

Open the derivative block and press the Help button to read the doc.
It explains why the derivative is zero, and has links to several topics related to why you should avoid using derivative blocks and how you may be able to change your model to avoid them.

Phil.