After much adou and angst I have managed to draw the attached 3-D sketch in an assembly file and copy it to a new part file. All the lines of the sketch are now black, However, the sketch has the following warning attached. "The sketch has not been updated because solving it would result in invalid geometry (such as zero-lentgth line.) Consider: *Deleting the invalid geometry *Changing relations or dimensions to eliminate the invalid geometry." I would like to fill in the area between the lines with something like a "Boundary Surface" but I can't, probably because of the warning. I have dimensioned the drawing, but it doesn't seem to help. There doesn't seem to be any invalid geometry.
On the surfaces tab tool bar, most everything is greyed out except "Extrude Surface" Revolved Surface" Lofted Surface" and Boundary Surface. However, none of these will except inputs from the sketch. I guess the question is what is wrong with this drawing? There are no gaps and all the corners are merged. What am I doing wrong?