Can't Login Paypal Sandbox with Test Email

I created an account in the sandbox both seller / bussiness now i am trying to use it on the site and developer test site which i have to select an account and press the "Enter sandbox test site" but still wont work. did it on the site but still no movement keep getting the Message.
Email: Please enter a valid email address. It must be in the format: username@domain.com. Your email address is different from your eBay ID.

Solution :

1. Log in to https://developer.paypal.com, click the Test Accounts tab, select the desired test
account, and click Enter Sandbox Test Site.
2. Open the HTML file containing the Buy Now Button.
3. Click the Buy Now Button.
4. Log in using your test buyer account.
5. Follow the on-screen instructions to complete your test payment.



For the step 1, I was initially logged into a seller account, but this didn't work. You need to login as a buyer for step 1, then click the Buy Now Button on your website, then login as a buyer again.



Hope this helps. If you find this is helpful to you plz mark this post as solution

Kudo