Why won't my AR subsidiary customer balances agree with the AR controlling account in the general ledger. They aren't the Same number. I just need to know what I dis wrong

cash $9,270 4. Assume Guardian Security Services began using a computerized accounting system the sales transactions on February 1. What are the of the computerized system over the manual system? PR 5-2B Revenue and cash receipts journals accounts receivable subsidiary and 08.2, 3 general ledgers receipts completed by Sterling Engineering Transactions related to revenue and cash Services during the period June 2-30, 2014, are as follows: June 2. Issued Invoice No. 717 to Yee Co., S1,430. 3. Received cash from Auto-Flex Co. for the balance owed on its account. 7. Issued Invoice No. 718 to Cooper Development Co., $670. 10. Issued Invoice No. 719 to Ridge Communities, $2,8i0. Post revenue and collections to the accounts receitable subsidiary ledger. 14. Received cash from Cooper Development Co. for the balance owed on June 1. 16. Issued Invoice No. 720 to Cooper Development Co., si00 Post revenue and collections to the accounts receivable subsidiary edger. 18. Received cash from Yee Co. for the balance due on invoice of June 2. 20. Received cash from Cooper Development Co. for invoice of June 7. 23. Issued Invoice No. 721 to Auto-Flex Co., $860. 30. Recorded cash fees earned, $4,520. 30. Received office equipment of s1,800 in partial settlement of balance due on the Ridge Communities account. Post revenue and collections to the accounts receivable subsidiary ledger. nstructions 1. Insert the following balances in the general ledger as of June 1 $18,340 12 Accounts Receivable 2,650 8 Office Equipment 41 Fees Earned 2. Insert the following balances in the accounts receivable subsidiary ledger as of June 1 $1,670 Auto-Flex Co. 3. Prepare a single-column revenue journal (p. 40) and a cash receipts journal (p. 36). Use the following column headings for the cash receipts jourmal: Fees Earned Cr., Ac- counts cr. and Cash Dr. The Fees Earmed column is used to record cash fees. Insert a check mark in the Post. Ref. column when recording cash fees 4, Using the two special journals and the two-column general the transactions for June. Post to the accounts receivable subsidiary ledger, and insert at the points indicated in the narrative of transactions, Determine balance in the account before recording a cash receipt. 5. l each of the columns of the special journals, and post the individual entries and totals to the general ledger. Insert account balances after the last posting 6. ine that the sum of the customer accounts agrees with the accounts receivable controlling account in the general ledger. hy would an automated system omit postings to a control account performed in step Accounts Receivable? as