How to verify a test (sandbox) account created in iTuneconnect

Hello,

I have created a test account using iTuneconnect, I received an email from Apple asking me to verify, clicked the link, enter my apple id and password, but I got error message saying:

Your request could not be completed.

Invalid account for this Email Address

What should I do? I logon to my account using the apple id and password, I can see the test account listed there.

Please help.

Thanks very much.