SUM(select(Customers_Aging_Exclude_Int[Customer Balance]/SUM(Monthly_Activity_DSO[Final Trx Amount]) *31, [Customer Number] = [_THISROW].[Customer Number]))

Customers_Aging_Exclude_Int = Current Table

Customer Balance = Column in the table

Monthly_Activity_DSO = another table

Final Trx Amount = Column in that table

Here is the error:

Column Name ‘Test DSO by branch’ in Schema ‘Customers_Aging_Exclude_Int_Schema’ of Column Type ‘Decimal’ has an invalid app formula ‘=SUM(select(Customers_Aging_Exclude_Int[Customer Balance]/SUM(Monthly_Activity_DSO[Final Trx Amount]) *31, [Customer Number] = [_THISROW].[Customer Number]))’. Arithmetic expression ‘(CUSTOMERS_AGING_EXCLUDE_INT[Customer Balance]/SUM(MONTHLY_ACTIVITY_DSO[Final Trx Amount]))’ has inputs of an invalid type ‘Unknown’

Column Types:

[Customer Balance] = Decimal

[Test DSO by Branch] = Decimal

[Final Trx Amount] = Price

[Customer Number] = Number