Having an issue with the "Draw Trace" syntax

All,

I am trying to do earthwork for one of our projects,and trying to get this as automated as possible. Here is the issue. I need to use the draw trace syntax on the first rock layer below existing ground. Please see the attached screen shot.

What I need to do is if the bottom of the 12 inches of compaction is between existing ground and the first layer of rock, I need to us draw trace to draw from the 12 inch line to where it intersects the layer of rock, and then draw trace along it until it hits the bottom of the AB-3.

I can get it to draw trace along the existing ground no problem, but I can't get it to draw trace along the first rock layer.

Here is the syntax I am using:

DRAW SKIP TO X101 Y101                           /* At Exist Ground */
draw trace in off = 0 to x317                           /*to AB-3*/
DRAW SKIP TO X301 Y301                           /*1st rock layer*/
draw trace "~MANTLE in DGN" in to x318   /*trace to AB-3*/
DRAW SKIP TO X317 Y317
draw slope = -pavement slope to X318
draw slope = -pavement slope to X316
DRAW TO X310 Y310

Thanks for your time.

Lawrence