Rooting a Erisin with *#hct#root# not working

Hi,

I tried to root my Erisin with the code *#hct#root#

The code works and the Radio "answers", but if I then try to install Viper for example, it doesn't work, saying it needs root access.
So I entered the code *#hct#root# and tried to install SU (and similar apps), but also without success.

Any idea?

Thanks
Markus