use xsign to sign symbian apps

Before I ever make interactive tutorial about sign Symbian applications using SignSis Tool (from OPDA), FreeSigner (from OPDA too) and the signed software from iMobile.
But before continuing, I have a little note in sign symbian application using software (offline signed).
Not all Symbian applications will being succeed in signing process, I had failed in some applications. Symbian applications can always be installed if the phone hack, but it is risky.