Hi
Have you configured alert using component based mechanism or have you configured in the traditional way?
For normal mechanism, check that the rule in active in RWB and present in the SXMSALERTRULES table.
If you have checked the suppress option, then you need to read the alert email in the alert inbox of RWB.
Also execute report SXMSALERT_LOGREADER using SE38 to check the rule is called or not.