in lite-c u add the "trace_mode" to the trace command itself (look for c_trace in the "online manual")

c_trace(startPos,endPos,IGNORE_YOU|IGNORE_PASSABLE|USE_BOX);

cheers

get the C# wrapper:
for A7.85.4 and A8.30.4, Version 2.3.9
at http://acknexwrapper2.matthias-auer.net/ or visit the thread