If the buyer has paid using PayPal and the payment doesn't show in your PayPal account activity or history page, the payment was sent to an email address which is not linked to your PayPal account.
You may have misspelled your PayPal email address in the payments section of your eBay listing or you may have used an old email address or you may need to confirm your email address.
To check which PayPal email address was used in the eBay listing, click on the "Relist" link for that item and look in the payments section for the PayPal email address.
If you have access to that email address, login to your PayPal account and "Add" the email address to your account. The payment will show up right after you confirm the email address.
If you do not have access to that email address, you will need to ask the buyer to cancel the payment and resend the payment to your correct email address. Send the buyer a PayPal invoice (Request Money) from your PayPal account to make it easier for the buyer to pay.
To check whether the email address needs to be confirmed, login to your PayPal account, click on the "Profile" tab and select the "Email" link in the left hand column. If it's not confirmed, click on the "Confirm" button to initiate the confirmation process.
For future eBay listings, make sure you have the correct PayPal email address in the payments section of each listing... here's a screen shot of that section of the eBay "Sell Your Item" form.
http://img.photobucket.com/albums/v635/dulcinea02/payment03b.gif
