I have one form 'Parent Registration' which includes an email field with the field name: Email

I have another form 'List a Job,' which has a lookup field correlating to the Parent Registration form. 

I want to add script from the List a Job form to send an email to the input email. The input email is originally in the Parent Registration form, but I thought this should still work as I have used the Parent Registration Form as a lookup field.

However I am getting the issue:

Error at line:3

Viariable 'Email' is not declared

Here is a screenshot: