Build a Model without source code

Hello,

I followed this tutorial in order to send only my simulink model with a s-function as obj to protect intellectual property:

https://uk.mathworks.com/matlabcentral/answers/196427-how-do-i-build-my-model-that-contains-an-rtw-generated-s-function-block-if-i-do-not-have-the-source

but I just can't seem to get it to work because when the receiver build the model, the build fails because it asks for the source code (.c file) again.

what do I possibly miss?