Tune Simulink parameter at simulation time

Hi to everyone,

I have a problem. I have an embedded function in my simulink model which has a structure (struct) as parameter. It contains only numerical values and I generate an S-Function of the embedded function by right clicking on the block and C/C++ code --> Generate S-function.

I then have the compiled block, if I try to change some values of my struct nothing changes (the fields of my struct stay the same as when I first compiled my embedded function).

When I compiled the embedded function block I selected the parameter to be tunable. I selected the parameter to be tunable in the Model Explorer. I tried to follow this video tutorial by mathworks: http://fr.mathworks.com/videos/tunable-structure-parameters-68947.html (The video is for r2010a while I am at r2015b) It is a bit different the interface in r2015b (from the one in the video) but when I click on Configure , like the guy does in the video, nothing happens.

Could you help me please?

Thanks a lot.