Rebuild.exe is part of the Visual COBOL development product and also part of the COBOL Server product.
Like other Visual COBOL components it requires both the COBOL run-time files and a valid license installed in order to run it so it can only be run if access to both of these requirements is made available.
You would either have to install the Visual COBOL or COBOL Server product or you would have to setup your system so that these products and licenses were available via network configuration.
Thanks.