I tested this in Access against the same Database/Tables and data is shon in access. However, when i run this as a Commnad in Crystal there is no data shown on the report.
SELECT Invoice_Header.Customer, Sum(Invoice_Header.Orig_Invoice_Amt) AS SumOfOrig_Invoice_Amt
FROM Invoice_Detail INNER JOIN Invoice_Header ON Invoice_Detail.Document = Invoice_Header.Document
WHERE (((Invoice_Header.Document_Date) Between 7/1/2014 And 6/30/2015))
GROUP BY Invoice_Header.Customer;
SELECT Invoice_Header.Customer, Sum(Invoice_Header.Orig_Invoice_Amt) AS SumOfOrig_Invoice_Amt
FROM Invoice_Detail INNER JOIN Invoice_Header ON Invoice_Detail.Document = Invoice_Header.Document
WHERE (((Invoice_Header.Document_Date) Between 7/1/2014 And 6/30/2015))
GROUP BY Invoice_Header.Customer;