Problem 219

I am trying to generate a pi-/pi+ beam and would like to track
the beam through a magnetic dipole field. I have the following strange
behaviour:
a) step length seems to be zero at the beginning (3 times)
b) -> 4th step -> the step length gets so large that pion "jumps" outside
   the experimental hall.
c) -> core dump

Electrons, Positrons, and Muons behave normally

Thanks for any help.

Wolfgang