Regarding of your error code:
MySQL error code 1044 (ER_DBACCESS_DENIED_ERROR):
Access denied for user ' '@'localhost' to database 'mydatabase'
Can you see=> ' '<=@
so, this means your are trying to login to that mysql server using anonym mysql user which is not allowed on shared hosts(on production servers)+obviously it has no grant to your 'mydatabase'
Where are you experiencing that problem? On your localhost (your PC) or in that "internet server"?
Are you trying to import that database using phpmyadmin?
Can you Print screen that exact operation when you get this error?(If possible)
IMHO: You have incorrect credentials mysql user/password or you have no proper grants for access that database called mydatabase.