When you add a bank account to paypal it sets up the direct debit mandate so that paypal can take authorised payments for any purchases you make (or pay your Ebay fees). No company eg water/electric can take funds from your bank account on a regular basis without that direct debit. However the amount shown is always the ''last'' transaction / amount that you paid to a seller via paypal.
Sometimes it does not coincide with the date you made the payment as paypal CREDIT the seller in advance and then paypal wait for the funds to transfer from your bank account, they can 'leave' that account at anytime from a few hours up to a few days later. Also the 'amount' can sometimes not be recognised if you used it as a part-payment with the rest coming from funds already in your paypal balance.
Advice is voluntary. Kudos / Solution appreciated.