Why do i get an error when i try to build C programmed s-functions?

The last two weeks I was able to build c programmed s-functions properly, but now, I don't know why, when I try to build the same s-functions that before i get the following message:

An unexpected error occurred during compilation. Please verify the following:
     -The MEX command is configured correctly. Type 'mex -setup' at 
      MATLAB command prompt to configure this command.
     -The S-function settings in the Initialization or Libraries tab were entered incorrectly.
      (i.e. use comma separated list for the library/source files)
     -If S-Function Builder dialog box in an invalid state, please restart
      MATLAB before using this dialog further.
Component: S-function Builder | Category: Build error

I'm using R2015a version of MATLAB and in my laptop the same file builds well in the same version, i'm already re-installed SDK 7.1, and re-installed MATLAB too, an run mex -setup and its seems to be okay, but i can't compile the s-functions.

Please help me, i don't want to reinstall windows and all the software again.