Curtin Ltd has a reconciliation problem. The bank reconciliation officer is unable to reconcile the cash at bank value recorded in the general ledger account with the cash at bank balance disclosed on the bank statements. Curtin Ltd seems to have good controls; it has separated all cash handling and recording functions from the bank reconciliation function, and it prepares a bank reconciliation on a weekly basis. 

a. Which internal controls might be missing?. 

b. What documentation would you examine in order to investigate this problem?