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Another thing that can help us to find out what's wrong is a log file: Before calling SetParams(), please add loSession.initLog(). Then, when you run XFRX next time, _XFRX.log file will be generated in the default directory. This file contains all errors that are trapped during XFRX execution. Attaching this file to the email is a big help for us. The alternative method is setLogFile().
Error messages are print to "Output Windows" too (since XFRX 15.8).
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If you have problems with a particular report, please attach it to your email as well (if possible). Also, if your report is not too entangled with your environment and you'd be able to provide us with sample data that we could use to run your report, it would help us a lot in finding out what the problem is. Do not forget to code snippet of calls XFRX (XFRX#INIT XFRX#INIT not is XFRX#LISTENERis XFRX#LISTENER).