rwbld60 is for Oracle Report 6i. The report you are trying to open was developed using a newer version of Report Builder though. Simply look for rwbuilder in ORACLE_HOME/bin/ instead of rwbld60 or install the newer version of Oracle Report Builder if you don't have it yet. Note, that you may have several Oracle Homes in your development environment so check them all or do a search for rwbuilder in your system. You have to use the same version of Developer Suite that was used for creating your report.