Sending email with specific subject if criteria is met

Hello,

I'd like to have my custom action send an email with a specific title if one criteria is met, and send an email with a different subject if it is not met. I tried doing this through the Conditional Action List feature and all my syntax was good but when I tried to apply it I got a validation error saying "Object reference not set to an instance of an object." I was using CurrentObject() for sending the emails. Not sure what to do to get the emails to work.

Thanks!