Very Computer

Here is my feeble attempt to explain what I'm doing:

In Coreldraw 6:
I have scanned a black and white line drawing and traced it with Corel OCR
using the 'outline' tracer (I liked the results of the tracing); then
imported the vector into Corel 6. The black outline became a silhouette
image underneath the white image.....which is fine because I can change the
color of the outline. BUT this silhouette/outline thing will not respond to
being trimmed or welded. I tried copying it and cloning it. I keep getting a
message that says 'the trim operation could not be completed on the selected
object (s). What is going on here?

Thanks!
Misha