I am trying to create a sketch on a sheet metal part and basically there are two places that are the same on each side that need to be extended, it is sheet metal and the person working on it before me did some stuff that I do not know how to do so i am just going the easy route and extruding it.  Hard to explain i can include a picture if needed.  But every time i create a sketch on the surface it will not let me create drawings.  The wierd thing is it did on the other half of the part but not this one.  Thanks!