ok so I've drawn a 2d sketch, I then try to end sketch and "Can not  rebuild the feature using this sketch". I choose the show the problem using check sketch option. It then says the sketch has no contour geometry to try to fix.. press ok. So I click ok. Default gaps smaller then setting is 0.0241069 and there's no problems found. I raise this to 800mm and 1 problem alerts "a small entity". A line is circled in yellow in the centre of it. i zoom in all the way and there are no breaks in the line and it is joined at the ends properly. I don't know what to do!!! I'm teaching myself how to use solid works and it's very frustrating! I've tried redrawing it, opening new sheets, restarting it.. nothing! Also I can't get a circle to snap properly to a line. Even drawing a simple circle then drawing a line to end on the circle it snaps on but when I zoom in it's actually not toucing or its over lappin. If I then try to trim it the whole line disappears. Please I've literally spent hours trying to fix this.