Callback on CGI task

System

I'm using TS 5.5.2. Did anyone experience the following problem before?

I have a CGI task, it has the following successors defined:
<successors>
<successorset description="Approve">
<succ v="TaskX"/>
</successorset>
<successorset description="Reject">
<succ v="TaskY"/>
</successorset>
</successors>

If I execute:
iwcallback <myCGI task id> "Reject" "my comments"
The workflow made transition to TaskX, not TaskY!

If I execute:
iwcallback <myCGI task id> 1 "my comments"
It made the proper transition to TaskY.

According to the manual, the above 2 command should give me the same result. Any suggestions on how to make it work without using the numerical return code? Since the iwcallback command needs to exist in a shared script, which can be used to reject tasks from any workflow templates. There is no guarantee that al the workflow templates specify the "Reject" successorset after the "Approve" one.

Thanks in advance!