New Download not letting me play/possibly issues of shifting over account to new game?

I try to log in using my account I had on Minecraft 1.5.2 and it doesn't seem to have transferred over to Minecraft 1.6.1. I have waited for a week and it says the password or username is wrong however Monteasie is the correct username and I changed my password to the same password and still the issues exists. Any suggestions?