Go in Rebug toolbox, press right once, then it says "System Mode" Change this from Normal to Rebug. This enables the Debug menu on XMB, Goto it then Change NP Enviroment from "Invalid" To "np" Then change your system mode back to Normal, Restore Your Original CID In PS3ITA Manager then goto Sign in and Should work.
Note: You have to change NP Enviroment everytime you switch to CEX and then back to DEX