Hi, I don't know how to use the program from Dr. Schmidtlein, contact him if you have a problem. The -L option used to give the path to appropriate libraries must be given to the compiler, not to the make program ... so add it inside your makefile (in CPPFLAGS and/or LDFLAGS). This should work. Anyway, I think that the socket library should be useless on linux (not sure), so just try to delete the -lsocket option and see if it works too. I take the liberty of forwarding this email to the mailing list as if any other user encounters the same problem, he should find the solution. Regards, Simon <div class="gmail_quote">On Tue, Feb 26, 2013 at 9:47 AM, Saeed Heidary <<a href="mailto:saeedheidary79@gmail.com" target="_blank">saeedheidary79@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Dear Simon You are right I was not so patient to search, although I saw the URL before, but I did not scrutinize it, please accept my apology. But the problem still exists. the procedure I am doing ... before compiling the GATE, I have tried to compile ecat Makefile and utils Makefile , If you take a quick look at INSTALL file in ecat, I have tried to do the same way the error '-lsocket' happened during installin the utils Makefile, even though I use "make -L /usr/lib/happycoders" , the problem was not solved. so I decided to ignore the utils and continue, after doing ccmake and configuring the paths (ECAT Home etc.) every things compiled but I still have the linking problem ! Any way, just I gonna have sinogram or projection in PET, the standard output of cylindricalPET is root so I used the Bin.Gate.C by Dr.shmidelton , but I could not applied it to my desire, is there any solution ? Many thanks in advance Saeed </blockquote></div>