Financial Reporting - Sumx without aggregating invoices

[AA622]

Hello 

I am creating a customer Posted Payment journal report. I need to show customer payments per invoice# and cust account

I am having this issue where my sumx measure is aggregating the original amount owed therefore not showing every record at the linel level. I am pulling the data from a table but converting the amount columns into measures (orig amount owed, payment amount[s]) The below visual demonstrates two tables. The top visual shows just the columns from the table, the below visual shows the measures.

Notice how the 10,000 amount is aggregated in my measure.

CustPaym_OriginalAmt = SUMX('Table','Table'[OriginalAmt])

How can i adjust my measure to ensure it doesnt aggregate the two 10,000 values per invoice# ? The issues is b/c there can be multiple payments made to the original amount over time. We wont necessarily get all 10,000 in one payment.