With newer versions of SuSE Linux, the kernel sources need to prepared and symbolic links are needed for the ncurses library:
 

1. ln -s ncurses/panel.h panel.h in /usr/include

2. make oldconfig in /usr/src/linux

3. make prepare in /usr/src/linux

4. make scripts in /usr/src/linux

5. cp /usr/src/linux-obj/Module.* /usr/src/linux

6. rpmbuild --rebuild dgrp-(version).src.rpm

7. rpm -i /usr/src/packages/RPMS/(architecture)/dgrp-(version).(architecture).rpm

Where version is the Digi RealPort driver version you are installing and architecture is the system architecture (i.e. i386, x86_64, amd64, etc..)