Thanks Erel that was the problem. I setup a desktop link to the build server to save typing every time, which did start it ok, but it did not see the libs folder. Got around it by aliasing a script which changes into the correct folder first then runs the server. In Windows and even debian I can make a desktop shortcut and tell it the working folder, OSX has yet to learn this. Just got it all working, another brilliant effort on your part. Thanks, my first app took about 20 seconds to make.Seems like the Libs folder is missing on your Mac computer. There should be a folder named Libs in the folder of B4iBuildServer.jar. All the libraries including iDesigner.h should be there.