compiling qpopper on SCO OS 5.0.5

[Don]

Hi,   I'm trying to compile Qpopper 4.0.3 on SCO OS 5.0.5.  I've made the changes to the make files but am getting the following error:   gcc: installation problem, cannot exec `cpp': No such file or directory *** Error code 1 (bu21) *** Error code 1 (bu21)   Using the SCO Open Server Development System.  Any ideas?