Getting a red error message about Invalid Password? Make sure you are using the UserLogin, NOT your alias. Make sure you are typing both UserLogin and password EXACTLY as it shows in the e-mail.
No error message, user/pass is right, but still not logged in? You probably have a cookie blocker on. Please allow GreenArrowStock.com to put cookies on your computer. They are simply session cookies that store your username/password. We don't use them to track anything.
If none of this works, e-mail us. Please provide as much detail as possible about the problem. 97.6% of the time, though, your login issue is one of the above.