i'm trying two different ways to use c_trace to make the player stick to the ground, but neither are working:

1)

(c_trace(my.x,vector(my.x,my.y,my.z-5000),IGNORE_ME | IGNORE_PASSABLE | USE_BOX) = downdistance);

my.z -= downdistance;


2)

if (c_trace(my.x,vector(my.x,my.y,my.z-5000),IGNORE_ME | IGNORE_PASSABLE | USE_BOX) > 0)
{
my.z = hit.z;
}



but the first one has a syntax error:
(c_trace(my invalid character

and the second one has the error message:
parameter unknown hit keyword


can somebody please help? thanks in advance