Alerts on mapping error from BPM

In my BPM, when I use 'Throw Alert' via control step before transformation, it creates an Alert.

What I would like to do is to Throw Alert when there is a mapping error. And in order to do this, I created an exception block within my transformation step and inserted an exception handler. And in the exception handler, I created control step with 'Throw Alert'.

When there is a mapping error, I do not get an Alert but throws an exception.

Is there anything I'm missing.

Thank you,

Parimala