Changing PSN id on the PSP

I used an old psn id on my psp, and now I can't change it to the one I am using now. Help ?

What?

Sign In under the account you want

You can't transfer ANYTHING including names

I guess thats what yur trying to say

If I try using the account I want I get an error saying that i can't use a different id, btw I tried formatting the memory stick and it didn't work.