Linux emu: ptrace attach - operation not permitted

[Mikle Krutov]

Hello, list!
For the start, i use linux emulation for playing
Dwarf Fortress game.
It has very handy utilset that helps maintaining
your fortress, DFHack & ui for it,
DwarfTherapist.
The problem is with running it, when trying to
run, i got:
ptrace attach -  operation not permitted
Both df and dfhack are running from the same
user, tried to run dfhack as root and got
ptrace attach: Invalid argument

What should i do to diagnose the problem?
and, if it is wrong arguments for ptrace,
how do i allow user to use ptrace attach?

-- 
with best regards, Krutov Mikle