Keep getting an error with psp iso in TacText

[Furry_Fan]

Ok I need help I know how to use FFTacText decently well with the psx iso but whenever I try to load the psp iso it gives me an error and I am unsure why.  I have taken the liberty to screen shot it and I was wondering if anyone could help me out.



I really do not know what it means and have never gotten it when trying to edit the psx iso.  So if anyone can let me know what I can do I would appreciate it very much.