Rounding piped text

Hello,
I'm trying to round the piped text WeightedMean to 2 decimal places. It works totally fine when it is in a custom end of survey message -- but when I insert the same code into an email trigger message, it doesn't seem to work at all.

Here's what I've done:

 $e{ round (gr://SC_719uI6wyHgEEi7c/WeightedMean , 2 ) }

Even when I copy and paste the message from my library into the email trigger -- the end of survey message displays no problem but the email that I receive from the trigger gives me an invalid expression message for the weighted mean.