The bottom window of the graphical interface displays status and error information. Furthermore, when you use the graphical interface, a history of each compiler run is saved in the pdtc.log file (in the \usrpdf subdirectory). The log is overwritten each time you start the compiler.
In addition to verifying that the PDT description is unique, the compiler checks that the syntax of the PDF is correct and errors are displayed. Use an ASCII editor to correct the errors and compile the PDT again.