Hi,
If you have the time I would use extended notifications instead of old and obsolete technology.
Regarding your issue.
1. has the user who executed the report have a valid email address ( xxx@yyy.zzz)
2. Are you able to send emails? (system-->short message)
3. is agent assignment of the task correct?
ad 2. Ask basis to setup SCOT properly
ad 3. Go to task in pftc, additional data-->agent assignment-->maintain. If this is the culprit then you can use report RHMOVE30 to transport these HR settings required by Workflow.
Kind regards, Rob Dielemans