making the Grade

[jigglehips]

RE: Civil 3D 2005 Grading
Hello,
I'm trying to create a simple cell design, just a hole in the ground with 1:3 side slopes. Then from around it's crest line project up to the restoration levels above. It seems to have problems using a 3D polyline to project up (I get an error message), LDT has no problem with exactly the same lines. If I break the 3D polyline into small simple sections it seems to cope better and actually creates a grading object. However, I then end up with multiple grading objects that aren't related to each other. When I explode them to trim the contour lines off, I can't because it says they aren't in the current UCS (it gives it an incorrect 'Z' value).
With regard to the trimming, I can't do it in AutoCAD 2004 now as well.

Any help would be fantastic as I've spent the last week bouncing from one problems to another.