Brokerage account

I have a brokerage account set up in Quicken with a balance of X $. I open the enter transaction box to enter a transaction and select Buy - Shares Bought, I enter all the info pertaining to the Buy but it does not always give me the option of what account to use for the purchase (in this instance, the same act) in lower left hand corner and thus does not reduce the balance in the account for the purchase. The cash amount column then shows N/A. Am I doing something wrong or is there a glitch. Sometimes the choice to choose the account shows in the lower left hand corner and when i start adding the purchase details it goes away. Same this also happens when i select Sell - Shares Sold, N/A and does not show the addition to the cash balance.