Problems with Paypal payment?

Call them they will talk you threw it.

There are sufficient numbers of PayPal horror stories to make the seller beware. 
Those who have been burned will gladly share their stories. It is not unheard of the disgruntled buyer can get his money back and not have to return the product. 
Its wise to check and confirm buyer feedback, and make a personal contact on big $$ sales. It only takes one bad apple. I have a local person who only deals in cash and in person from the welt he endured from PayPal.

I had a problem with accessing PayPal just the other day. It is an Audiogon issue or requirement (take your pick). If the item you are buying is a "Buy it Now" sale, you cannot access PayPal until you select the "Add Credit Card" button and add a credit card, which Audiogon claims they do not retain. Once you complete this seemingly useless task, PayPal is enabled.

I've had good experience with Paypal over the years, but I try to be careful to ensure I'm not getting scammed by anyone.

My experience is mostly with camera gear, not audio, but overall, the photo community is pretty reasonable and honest, but there are scammers about , so you have to be careful, as you do with audio gear as well.  Just don't sell on Ebay...

Even PP's fees are reasonable as far as I'm concerned.  Without having a full business infrastructure, there really aren't any other payment methods that are widely accepted and that have lower fees.  Yes, the fees used to be better, but they are overall competitive with anyone else I've looked into in the past.

As for my original question, there is a hitch in the A-gon website that makes it appear that it is calling on PP to sign in, but it apparently doesn't quite handshake with the site correctly.  I had changed my PP password a while ago, and so A-gon was passing it an old password.  Not sure why they are even storing a password on their site at all anyway.  I'm not sure I like that one bit.  They should only be setting up the handshake and allow my local browser to make the handshake, but that's not what occurs.

Anyway, I got it working.  Thanks for the comments and help folks.

I had a very similar issue just 2 days ago. PP told me it was Agon issue, Agon says it's PP issue. Go figure.