Create New Field/ Check Syntax: "Missing Braces"

Create New Field/ Check Syntax: "Missing Braces"

Hello,

I need some help regarding my CRM app for  Zoho. 

In the potentionals, I have "annual usage" and "margin"

I need to multiply the two fields together to get "annual revenue".

${Potentials.Annual Usage}*${Potentials.Margin ($ per kWh/Therm))}

I tried to program a field and  Zoho returned the following message: "Missing Braces". I cannot find any help files or blogs that can help. Can you have someone reply or reach out to me? This is very time sensitive. Thank you.