Email webi report based on the Rules

Hi,

I have to email a report based on the custom rule created in the webi. I have an ID and Event date in the report and on every refresh if the id or Event date changes i have to color the text in red and send out an email with the report.

I tried creating a rule with the previous(ID) <> ID or previous(date) <> date, but on validation it is asking to return a boolean value.

Any suggestions or work around or any other way to implement this?

Thanks,
Arun