feko

hi everyone
i try to simulate a reflector by size of .85 meter in cst.but i cant.then i go to feko because i see a example from feko that simulate a 1.3 meter reflector in 2 hours.
i import the reflector and the feed to feko.but i have a problem.it show an errorerror240:a triangle is too small or epsent is too large).
im realy in urgent.:sad:
thanks in advance.