TString pointer becoming NULL

Dear all,
I am trying to read some data from a file (3 columns: string float float) to fill an histogram.
The problem I have is that the TString** array, filled in the loop where I read the file, gets out of scope
when I loop again over it to read the strings back. A similar script worked for me in the past.
In attachment you can find the macro I am using and a txt files to be passed to the macro itself.

I am using ROOT 6.04/08 and the output I get is:

Am I missing something?

Many thanks in advance and best regards,
Marco Bomben
vdepl_Perugia2015_fl1e15.txt (215 Bytes)
read_and_draw_vdepl_Perugia2015_fl1e15.C (1.18 KB)

read_and_draw_vdepl_Perugia2015_fl1e15.C (1.46 KB)