Error messages when there are no errors in OWB

It appears that oracle warehouse builder (OWB) will tell you have an error even though there is no error. Case in point, while creating a process flow, I had a Stored Procedure from a package returning back a Boolean value. I use this return value to determine the transition to the next activity as seen in figure 1.
















figure 1



I set the complex condition "PFUNC_RACS_AVAILABLE"."P_BAVAILABLE" for end with success. I then set the end with errors with NOT "PFUNC_RACS_AVAILABLE"."P_BAVAILABLE" . Finally I set no condition for end with warnings. But when I did a validation on the condition, OWB said I had an error in the expression (figure2). The error was PLS-00530: Illegal type used for object.
















figure 2



Now since I have been working in OWB for a while, I have learned oracle not only gives bad error messages, but incorrect ones as well. Therefore I question most messages from Oracle and decided to test the process flow to make sure. In the figure below, the test shows the flow did work correctly. The second test I simply reversed the conditions between success and errors.









figure 3



As another test I checked the results in the control center to see what was returned from the procedure. Sure enough, a Boolean value was returned. I even reversed what was return to make sure I would be getting a false value (see figure 4).











figure 4