First, when you have an issue, please try to read the log file/trace that Project-Builder.org produces. 99% of the time, the error is described in it in clear text. To make the error more clear, and debug easier, fill free to increase verbosity by adding at least 2 "-v" options.
Second look at the Project-Builder.org documentation, as a lot of good tip and tricks are provided there as well as in the Wiki's FAQ and Documentation.
Third look at the Project-Builder.org wiki which may contain additional comments,and feel free to contribute by adding your remarks.
Fourth look at the Project-Builder.org Mailing List Archives (or this Gmane or Nabble mirror) as you're probably not the first with this problem. Or look at existing bug reports.
Fifth, if you're willing to help debugging the future Project-Builder.org versions, try the latest beta available under the test directory of our ftp server.
Finally post on the Project-Builder.org Mailing List if you did not find what you were looking for, as there are other users there who could help you, including dev team members.
If your think you found a bug in Project-Builder.org, please fill a bug report and also include the log files.
Likely, if you wish Project-Builder.org had your dreamed new shiny function, feel free to create a feature request.
There are 2 mailing lists for the Project-Builder.org Community: