I believe I had this same issue. I noticed after looking at the build log that $(SolutionDir) adds a backslash, so the command line is not properly linking to the correct file path. So instead, do $(SolutionDir)gsoap-2.8\gsoap\bin\win32\soapcpp2.exe -S $(InputPath)
Extra backslash
I believe I had this same issue. I noticed after looking at the build log that $(SolutionDir) adds a backslash, so the command line is not properly linking to the correct file path. So instead, do $(SolutionDir)gsoap-2.8\gsoap\bin\win32\soapcpp2.exe -S $(InputPath)
Remove the extra "\"