Anyone know a 'back door' into PayPal?

[JollyElm]

Here is the problem...

I'm negotiating with a seller on eBay, and I want to purchase the card in question at the price he is willing to sell it for. However, I need to use my credit cards points to defray some of the cost (without CC points the price is, well, a rip-off). When I go to pay for things on eBay using PayPal, sometimes it brings me to PayPal and allows me to click the box and use my points, but the vast majority of times (including now!) the window appears and has me sign in, and then POOF!! it disappears and I'm back at eBay's checkout page with the only option being "Pay Now." (For some reason, when I have my credit card itself selected as the payment type, it gives no option to use my points either, just "Pay Now.")

Is there a way to sign into PayPal first to pay for an auction? In other words, is there a way to avoid the situation I described above? Being able to use my CC points is such a random occurrence with PayPal, as there doesn't seem to be any rhyme or reason involved. I bought two separate cards just the other day, and both gave me the option of using my points, but I didn't. It seems to come and go. To be clear, I am not trying to avoid using eBay or do anything against the 'rules.' I want it to be an eBay purchase through my credit card via Paypal.

Anybody have any insight? Is there a way for the seller to send me an invoice, so it brings me directly to PayPal, or allows me to directly use my credit card points??

I'm sure a whole bunch of other people here would like to know the answer to this, too.

(There are no other issues, like my points were already used and whatnot. And I've done everything involved with refreshing the window, throwing out preferences, changing and re-changing payment types, etc. The issue is as straightforward as I presented it.)