Create a Rollup Summary Field

We created an account with one opportunity. We expected the account's 'Potential_Value' field to show the amount of that one opportunity, but it didn't.

What am I doing wrong? Thanks for sharing your ideas.

#Rollup Summary Field

https://trailhead.salesforce.com/content/learn/modules/point_click_business_logic/roll_up_summary_fields?trail_id=force_com_admin_intermediate&trailmix_creator_id=strailhead&trailmix_slug=build-your-admin-career-on-salesforce