trouble logging in

i am having trouble logging in. i can log in to my domain alone, but when i try logging into a subdomain, i get access denied why. someone please help.

I think there was some confusions so I will try to help a little better.

Heres my problem. Smartftp is installed correctly. I am able to login into my domain, but there is a problem. I can not login to any of my subdomains. I even have sites on subdomains that are not my domains and I am still unable to login. I keep getting this error 530 for some odd reason. It can not be my password. I keep using the same one. I just dont know what to do. I tried reinstalling it. Done that a couple of times. If anyone has a solution I would be happy to know what it is.