Getting error when working with Paypal Sandbox

I am trying to test my form: http://retrieverlife.com/breeder-listing/ and I am getting an error when I log into Paypal after I submit.

- I have logged into may paypal sandbox as the buyer account I set up prior to beginning this process
- Fill out the form and press submit
- Paypal presents a login screen for the sandbox.
- I enter the correct email and password for the buyer and press the login button
- I get the following message: The link you have used to enter the PayPal system is invalid. Please review the link and try again.
- I am using Windows 7, Google Chrome, IE 9

I think it has something to do with the IPN (I am using the one you folks supplied) but I am not sure.

Any ideas?

I am having this issue as well, trying to help test the issue outlined in this thread: http://www.gravityhelp.com/forums/topic/entry-payment-status-is-processing-%E2%80%94-paypal-has-no-record-of-these-submissions

I am trying to run a test, but even though I'm using a valid seller sandbox email in the PayPal Transaction Settings, when I click submit on the form to test, it goes to the LIVE paypal page instead. What am I doing wrong?

yes